report blackmans bay wastewater treatment … blackmans bay...2014 and summarised in the ‘report...

REPORT

Blackmans Bay Wastewater Treatment Plant

Odour Impact Assessment

Prepared for BMD Acciona JV

26/7/2016

Blackmans Bay WWTP Odour Impact Assessment

Status: Draft for Comment Project No.: 83503021 26/7/2016 Our ref: C:\Users\David\Dropbox\Projects\J1517 - Blackmans Bay STP ECI Bid\Odour Modelling\83503021-P-002 Blackmans Bay Odour Impact Assessment Report_Rev C.docx

This document has been prepared for the benefit of BMD Acciona JV and TasWater. No liability is accepted by this company or any employee or sub-consultant of this company with respect to its use by any other person.

This disclaimer shall apply notwithstanding that the report may be made available to other persons for an application for permission or approval to fulfil a legal requirement.

QUALITY STATEMENT

PROJECT MANAGER PROJECT TECHNICAL LEAD

Ari Shammay Ian Evanson

PREPARED BY

………………………………............... ……/……/…… Georgina Hale

CHECKED BY

………………………………............... ……/……/…… Ian Evanson

REVIEWED BY

………………………………............... ……/……/…… Ian Evanson / Jenny Barclay

APPROVED FOR ISSUE BY

………………………………............... ……/……/…… Ari Shammay

SYDNEY Level 21, 141 Walker Street, North Sydney, NSW 2060 PO Box 1831, North Sydney, NSW 2060 TEL +61 2 9493 9700, FAX +61 2 9493 9799

REVISION SCHEDULE

Rev No

Date Description Signature or Typed Name (documentation on file).

Prepared by Checked by Reviewed by Approved by

0 27/7/16 Initial issue GH IE IE/JB AS

C 28/7/16 For issue to TasWater GH IE IE/JB AS


BMD Acciona JV

Blackmans Bay WWTP Odour Impact Assessment

CONTENTS

1 Introduction ............................................................................................................................... 3

2 Site Description ......................................................................................................................... 3

2.1 Odour Complaints ................................................................................................................ 4

2.2 Process Summary ................................................................................................................ 6

2.3 Odour Emission Sources ...................................................................................................... 7

2.4 Odour Constituents by Plant Area ........................................................................................ 9

2.4.1 Preliminary Treatment ................................................................................................. 10

2.4.2 Secondary Treatment .................................................................................................. 10

2.4.3 Sludge Area ................................................................................................................. 10

3 Modelling Methodology ........................................................................................................... 12

3.1 Modelling Approach ............................................................................................................ 12

3.2 Meteorological Data and Model Run Period ....................................................................... 12

3.3 Dispersion Options ............................................................................................................. 13

3.4 Terrain Elevations .............................................................................................................. 13

3.5 Sensitive Receptors ........................................................................................................... 14

4 Odour Assessment Criteria ..................................................................................................... 16

5 Odour Impact Assessment ...................................................................................................... 17

5.1 Scenario 1 – Normal Operation of the New WWTP............................................................ 17

5.1.1 Odour Emission Data and Assumptions ...................................................................... 17

5.1.2 Modelling Results ........................................................................................................ 20

5.2 Scenario 2 – Inlet Works Maintenance Period for the New WWTP .................................... 21

5.3 Odour Emission Data and Assumptions ............................................................................. 21


5.4 Scenario 3 – Upset in the Treatment Process for the New WWTP .................................... 23


5.5 Modelling Results ............................................................................................................... 24

5.6 Scenario 4 – Upset in the Sludge Processing for the New WWTP..................................... 25



5.7 Scenario 5: Commissioning Works ..................................................................................... 27


5.7.2 Assessment Results .................................................................................................... 28

6 Odour Assessment Summary ................................................................................................. 29

6.1 Predicted Odour Concentrations at Sensitive Receptors ................................................... 29


6.2 Time of Day Impacts .......................................................................................................... 30

6.3 Management of Odour Impact during Adverse Weather Conditions .................................. 30

6.4 Management of odour during biosolids export ................................................................... 30

6.5 Management of odour during construction ......................................................................... 31

7 Summary and Conclusions ..................................................................................................... 31

LIST OF TABLES

Table 2-1: Odour complaint history (IHMS) ...................................................................................... 5

Table 2-2: Omitted process units in the Blackmans Bay WWTP dispersion model .......................... 7

Table 2-3: Odour emission rate derivation for the Blackmans Bay WWTP dispersion model .......... 8

Table 3-1: Sensitive receptor locations used in the modelling ....................................................... 15

Table 5-1: Point emission source locations .................................................................................... 18

Table 5-2: Odour emission data input into the model for point sources ......................................... 18

Table 5-3: Area emission source locations ..................................................................................... 18

Table 5-4: Odour emission data input into the model for area sources .......................................... 19

Table 5-5: Odour emission data for area sources in Scenario 1 and Scenario 5 ........................... 27

Table 6-1: Predicted 1-hour average, 99.5 percentile odour concentrations (ou) at sensitive receptors for Scenarios 1-4 ............................................................................................................ 29

Table 6-2: Predicted 1-hour average, 100 percentile odour concentrations (ou) at sensitive receptors for Scenarios 1-4 ............................................................................................................ 30

LIST OF FIGURES

Figure 2-1: Site location map with existing site boundary (red line) and future site boundary (blue line) 4

Figure 2-2 : Odour complaints and community odour monitoring ..................................................... 5

Figure 2-3: Existing Blackmans Bay WWTP site layout.................................................................... 7

Figure 2-4: Compounds produced via sludge storage after dewatering ......................................... 11

Figure 3-1: Terrain elevations at the site and discrete receptor grids ............................................ 14

Figure 3-2: Aerial base map showing the project site and sensitive receptor locations ................. 15

Figure 5-1: Aerial image showing the emission source locations for Scenario 1 ............................ 20

Figure 5-2: Blackmans Bay Scenario 1 odour concentration contour plot ...................................... 21




APPENDICES

Appendix A Tender Design Site Layout Drawing

Appendix B Odour Source Model Input Tables

Appendix C Input Meteorological Data Report


1 Introduction A significant augmentation is planned for the Blackmans Bay Wastewater Treatment Plant (WWTP) under TasWater’s Kingborough Sewerage Upgrade Project. MWH were engaged to investigate the potential odour impact from the new WWTP as part of the BMD Acciona Joint Venture (BAJV) tender design. A history of odour issues at the current site, coupled with regulatory compliance requirements, has been the basis for the odour impact assessment and the driver for key design features for the augmentation.

Odour impacts from the facility were previously modelled by Consulting Environmental Engineers in 2014 and summarised in the ‘Report on Odour Modelling for Blackmans Bay Wastewater Treatment Plant’, Consulting Environmental Engineers, April 2014 (CEE Odour Modelling Report, 2014).

The requirement for the augmentation of Blackmans Bay WWTP is to achieve no nuisance odours at nearby residences, together with meeting the odour criteria under EPA Tasmania’s Environment Protection Policy (Air Quality) 2004 (which requires an odour limit of 2 ou based on a 1 hour averaging period and 99.5% compliance, measured at or beyond the facility boundary).

MWH used data and information provided by TYR Group and TasWater to produce a CALPUFF odour dispersion model of the new site, including:

1. Meteorological modelling using hourly observational data from the Bureau of Meteorology’s four nearest meteorological stations (Dennes Point, Hobart, Kunyani and Grove) plus a single upper air station, Hobart Airport. Two models, the Australian CSIROs the Air Pollution Model (TAPM) and CALMET, the diagnostic meteorological component of the CALPUFF suite of models, were used to develop the meteorological data set at the WWTP; and

2. The latest available process and site layout information from the BAJV concept design.

The dispersion model inputs and results are summarised in this report, including an assessment of compliance against EPA Tasmania regulatory requirements.

2 Site Description Blackmans Bay WWTP is located on the western shore of the lower Derwent estuary, on the headland south of the Blackmans Bay residential development and to the east of rural residences. A site location map is provided in Figure 2-1.

According to the Kingborough Council Planning Scheme 2000, the area containing the treatment plant and land immediately to the west is zoned primary industries. The strip of houses along Suncoast Drive and land further north is zoned residential. An area of recreational land use exists to the south of the facility, most likely used by the general public for exercise, bushwalking and by the local Scouts group.

The existing site boundary is shown as the red line in Figure 2-1 and the blue line represents what this report refers to as the ‘future site boundary’. The latest available information from TasWater suggests that approximately 7.3 ha of land surrounding and containing the existing WWTP may be purchased from Council by TasWater. Both the existing and potential future site boundaries are shown on the odour concentration contour plots in Section 5 and have been used in the assessment of odour compliance.


Figure 2-1: Site location map with existing site boundary (red line) and future site boundary (blue line)

2.1 Odour Complaints

The existing site has historically been the source of odour complaints. The complaint data available (CEE Odour Modelling Report, 2014) has been combined with the provided Incident/Hazard management System (IHMS) Summary Report data and is presented in Table 2-1. It shows that the majority of the complaints arise from the houses to the north of the facility located on Suncoast drive , Liberty Crescent, and Tahune Crescent.

Figure 2-2 shows the location of the odour complaints (green dots) and those residences reporting odour in community odour logs (pink dots).

Treatment Plant Rd

Google Earth Pro 7.1.1.1580


Figure 2-2 : Odour complaints and community odour monitoring

Table 2-1: Odour complaint history (IHMS)

Date Location Notes

6-Jan-16

99 Suncoast Drive Blackmans Bay

Rang the call centre complaining about odour from the Blackmans Bay STP. The plant had a process change happen in the aeration tank between Christmas and New Year, the solids were not settling in the secondary clarifier. Ops increased the aeration and reduced the MLSS in the tank to try and rectify the problem. This action has overloaded the primary clarifier and some odour is noticeable around the perimeter of the plant. Also today the centrifuge brake system has broken down and Alpha electrics have been engaged to remove / repair, hopefully this work will be done by tomorrow and the centrifuge will be back up and running.

29-Jun-15 23 Tahune Crescent, blackmans Bay Odour complaint

10-Feb-15

11 Tahune Cres, Blackmans Bay Odour complaint

22-Dec-14

99 Suncoast Drive Blackmans Bay

Advised of strong sewage from the TP today. Inspected the treatment plant and a slight odour detected around the primary clarifier facility, the inline centrifuge is worn out overloading the primary clarifier with extra solids.

17-Nov-14

46 Suncoast Drive, Blackmans Bay Odour complaint

5-Nov-14 71 Suncoast Drive, Blackmans Bay Odour complaint

10-Oct-14 19 Tahune Cres Blackmans Bay

Complaining of sewage odours today and over recent weeks. Has been very good over recent months but deteriorated over last week or so.

23-Jul-14 99 Suncoast Drive Blackmans Bay)

Described odour as really offensive and making her child dry reach. Winds light and conditions mild today. Inspected area and Blackmans Bay plant. No odour at residence by 9.45 am, although some odour noticeable around the plant. All systems functioning as normal.



Date Location Notes

12-Feb-13

22 Tahune Cres Blackmans Bay

Odour complaint detailing ongoing odour issues over the weekend and also over the last 5-6 weeks.

31-Jan-13 Possible source of odour on Thursday we had a contractor doing some work on the centrifuge rollers (replacing rollers & realigning the belt) he needed access to the centrifuge room with his work van so he had to back up to the main roller door to do the work .so the door was open for about 5-6 hrs while he carried out his duties. This could have upset the drawing capacity of the odour fan and ducting system & possibly caused the odour.as all other areas of the plant were working all right & we were not running the centrifuge that day.

7-Jul-12 Odour complaint

1-Oct-11 99 Suncoast Dr Blackmans Bay

I am writing to you to advise that there has been a terrible smell coming from the treatment plant over the weekend and today it was even worse. We went for a walk yesterday (Sunday) and you could smell the odour from the top of Suncoast Drive.

31-May-10

Odour complaint believed to come from Blackmans Bay treatment plant. Resident said that the odour has been on and off for about 10 months but was bad at the moment.

10-Apr-10 Liberty Crt Blackmans Bay

Odour complaint regarding Blackmans Bay treatment plant.

2.2 Process Summary

The existing treatment process at Blackmans Bay WWTP is currently operating at its design capacity of 4.2 ML/d (million litres per day). The facility uses a combination of treatment processes including screening, grit removal, primary sedimentation, biological secondary treatment and chlorine disinfection to achieve the required treatment. A site layout diagram is shown in Figure 2-3.

The inlet / screening area and biosolids handling equipment is housed in a building to the north east of the site, next to anaerobic digestion facilities. Foul air from the inlet works / screening and biosolids building is treated in a large open-bed type biofilter. Biogas is flared off in a waste gas burner located in the north east of the site.

The disinfected secondary effluent from the plant is discharged through a diffuser via an outfall extending to 14 m depth within the estuary. The diffuser produces a high dilution – generally in the range of 120:1 to 200:1 – and the effluent field is often submerged at 3 to 5 m below the surface waters on the interface between the saline and surface waters. A site layout of the existing facility is shown in the figure overleaf.

The plant is at capacity and will be significantly augmented. The new WWTP will increase capacity from 4.1 ML/day to 8.5 ML/day, improve effluent quality and ensure discharge into the Derwent Estuary complies with environmental regulations. The BAJV process design comprises an inlet works, suspended media secondary treatment process, sludge thickening, aerobic digestion, dewatering and storage prior to removal off-site. The latest available general arrangement drawing of the new WWTP (provided by TYR Group) is included in Appendix A.


Figure 2-3: Existing Blackmans Bay WWTP site layout

2.3 Odour Emission Sources

A number of process units on-site were not included in the odour dispersion model since they are considered unlikely to generate odour emissions and cause environmental nuisance. These sources are listed in Table 2-2.

Table 2-2: Omitted process units in the Blackmans Bay WWTP dispersion model

Process Unit Explanation

Chlorine contact tanks (2No.)

The contents of the chorine contact tanks (chlorinated final effluent) are not known to emit an odour that causes offence. As such their inclusion would "skew" the model showing impact where there is none. They have therefore been excluded from the model.

Thickened sludge pump station

The thickened sludge pumping station is effectively just external pumps extracting from the gravity thickener. There is no liquid surface as such, other than that included for within the gravity thickener, thus no emission rate to surface in contact with the atmosphere.

Centrifuge and conveyors

Centrifuges, by definition, are sealed units. The odour from centrifuges is emitted from the centrate and sludge discharge lines. Both of these discharge lines will be sealed to the centrifuge and extracted from at a high rate as part of the augmentation works. After the augmentation works, the sludge at the point of dewatering (aerobically digested) will be of very


Process Unit Explanation

low odour potential, with the odour emission increasing as the sludge is stored post thickening (due to the action of shear and subsequent release of protein). As the sludge is of low odour potential at that point, and the discharge lines will be fully sealed with a high rate of extraction, this source has been excluded from the model.

Leakage from the dewatered cake self-loading bin, where anaerobic activity on the released protein will cause rapid production of odour driven by the release of reduced sulphur compounds, has been included in the model.

In order to obtain an indication of possible odour levels at Blackmans Bay WWTP, MWH have utilised the MWH Global Database to develop emission rates for inclusion in the dispersion model . The MWH Global Database contains over 8,000 odour sampling results taken from wastewater treatment plants in Australia, New Zealand, the Middle East and UK. The database is the largest of its kind worldwide, with emission rates categorised via equipment type, influent contaminant load and type, industrial loads, operation parameters, temperatures and geographical location. Data from only Australian WWTPs have been used in the modelling exercise.

Table 2-3 provides a summary of the specific odour emission rates (SOERs) and odour concentrations selected from the database for use in the model. Justification for the selected odour emission dataset is provided in the table. Scenario specific source tables are provided in Appendix B.

Table 2-3: Odour emission rate derivation for the Blackmans Bay WWTP dispersion model

Odour Source SOER

(ou.m/s) Notes

Inlet Works (screenings handling, grit classifier, bins)

4.47 Assumed to be a domestic network, dosed with Magnesium Hydroxide Liquid (MHL) to pH~8.5, relatively low temperature, and relatively aged sewage. Some potential industrial discharges (e.g. ‘Tassal’ fish processing, landfill leachate), but connection of these streams has not been agreed and they would be subject to pre-treatment prior to discharge to sewer. Thus, they have not been included within the estimate of the SOER. SOER based upon average of 10 odour samples taken from NSW sewage treatment facilities with similar inflows to the assumptions made.

Flow Distribution Channel

4.47

Inlet Works Return Pump Station

4.47

Assumed to be equal to the inlet works SOER for a conservative viewpoint General Purpose

Pump Station (centrate return)

4.47


Odour Source SOER

(ou.m/s) Notes

IDEA-SBR 1 Anoxic Selector Zone

1.70 90%ile of 18 SOER data points taken from anoxic selector zones on NSW / NZ sites

IDEA-SBR 1 Secondary Anoxic Zone

0.695 Average of 18 SOER data points taken from anoxic zones on NSW / NZ sites

IDEA-SBR 1 Aeration Phase

0.313 90%ile of 14 SOER data points taken from IDEA / SBR zones during aerobic phase on NSW sites (>20 day sludge age)

IDEA-SBR 1 Anoxic Phase

0.695 Assumed to be equal to the secondary anoxic zone emission (conservative)

IDEA-SBR 1 Settling / Decant Phase

0.076 Average of 18 SOER data points taken from equivalent decant phases on NSW / QLD sites

IDEA-SBR 2 Anoxic Selector Zone

1.70

As per IDEA-SBR 1


0.695

IDEA-SBR 1 Aeration Phase

0.313

IDEA-SBR 1 Anoxic Phase

0.695

IDEA-SBR 1 Settling / Decant Phase

0.076

Gravity Thickener 0.20 90%ile of 10 SOER samples for open gravity thickener for WAS. Assumed sludge is not stored in the gravity thickener tank.

Aerobic Digester - Aerobic Cells

0.15 Average emission from aerobic digester during aeration phase (6 samples from QLD sites for conservative view)

Aerobic Digester - Anoxic Cells

0.30 Peak emission from aerobic digester during anoxic phase (6 samples from QLD sites for conservative view)

Dewatered Cake Self-Loading Bin

29.38

Conservative view, SOER of anaerobically digested dewatered sludge, aged for 12 hours after dewatering in an enclosed bin. Anticipated that aerobically digested sludge will be of a lower magnitude.

Odour Control Facility Stack

n/a 500 ou discharge concentration (biotrickling filter / activated carbon two stage)

2.4 Odour Constituents by Plant Area

The expected constituents of the gas streams that make up the odour are detailed below. The concentrations of each constituent will general seasonal daily and hourly cyclic variances due the changes in sewage composition, or storage time of products.


2.4.1 Preliminary Treatment

The main odour constituents are;

Hydrogen sulphide gas (odour threshold 0.008ppm, rotten egg odour): generated within the sewerage network by anaerobic conditions and resulting sulphate respiration. The concentration of gas will vary seasonally due to eth variance in temperature, and daily due to wastewater flow changes. Increasing temperature and decreasing wastewater flow will produce elevated concentrations. Generally will be at concentrations (under covers) anywhere from 10 to 50ppm.

Methyl mercaptan (odour threshold 0.14-0.18ppb, decayed cabbage / garlic odour): generated via anaerobic breakdown of protein in wastewater. Generally will be at concentrations of 0.5 to 1 ppm under odour containment covers.

Dimethyl sulphide (odour threshold 012-0.4ppb, decayed vegetables / Putrefaction): again generated via anaerobic breakdown of protein in wastewater. Generally will be at concentrations of 0.5 to 1 ppm under odour containment covers.

Ammonia (odour threshold 130ppb, sharp pungent odour): generally associated with digested sludge returns. Generally will be at concentrations of 1 to 5 ppm under odour containment covers, reducing when anaerobic digestion is ceased.

Volatile Organic Compounds – VOCs (Odour threshold from 1ppb to 100’s ppm and varying odour type depending upon species). From household waste and industrial discharges (such as landfill leachate). Compounds vary significantly depending upon discharge, but generally include aromatic hydrocarbons, aldehydes, ketones, and alcohols. Chlorinated hydrocarbons are also usually present.

2.4.2 Secondary Treatment

The main odour constituents are;

Hydrogen sulphide gas (odour threshold 0.008ppm, rotten egg odour): Generally below 0.1ppm due to rapid oxidation in aerobic zone.

Methyl mercaptan (odour threshold 0.14-0.18ppb, decayed cabbage / garlic odour): Generally not detected due to rapid oxidation

Dimethyl Sulphide (odour threshold 012-0.4ppb, decayed vegetables / Putrefaction): Generally not detected due to rapid oxidation

Ammonia (odour threshold 130ppb, sharp pungent odour): Generally not detected due to rapid oxidation and high odour threshold

Volatile Organic Compounds – VOCs (Odour threshold from 1ppb to 100’s ppm and varying odour type depending upon species). From household waste and industrial discharges (such as landfill leachate). Compounds vary significantly depending upon discharge, but generally include aromatic hydrocarbons, aldehydes, ketones, and alcohols. Chlorinated hydrocarbons are also usually present.

2.4.3 Sludge Area

The aerobic digester should not produce / cause emission of significant odorous compounds. VOCs are emitted, together with very low concentrations of sulphur compounds – however this source is not related to odour complaints.

The main odour constituents are generated in the dewatering and storage of sludge. Dewatering sludge applies shear forces to the floc which releases protein. The greater the shear force applied, the more protein is released. This protein is then converted to odorous compounds via anaerobic activity during storage as per the cycle below.


Figure 2-4: Compounds produced via sludge storage after dewatering

Hydrogen sulphide gas (odour threshold 0.008ppm, rotten egg odour): concentration in storage generally in the 1 to 10ppm range depending upon storage duration.

Methyl mercaptan (odour threshold 0.14-0.18ppb, decayed cabbage / garlic odour): concentration in storage generally in the 5 to 20ppm range depending upon storage duration.

Dimethyl Sulphide (odour threshold 012-0.4ppb, decayed vegetables / Putrefaction): concentration in storage generally in the 1 to 10ppm range depending upon storage duration.

Ammonia (odour threshold 130ppb, sharp pungent odour): Generally not seen in aerobically digested sludge.

Volatile Organic Compounds – VOCs (Odour threshold from 1ppb to 100’s ppm and varying odour type depending upon species). Generally in the 1 to 5ppm range.


3 Modelling Methodology

3.1 Modelling Approach

The atmospheric dispersion modelling assessment has been undertaken using CALPUFF (version 7.2.1, level 150618). It was considered that the CALPUFF model would represent the dispersion of odour at the project site better than a Gaussian plume dispersion model such as AERMOD or AUSPLUME.

CALPUFF has been used extensively in Australia and New Zealand and is a recommended model in the New South Wales Office of Environment and Heritage’s (NSW OEH) Approved Methods (OEH, 2005)1, particularly for sites surrounded by complex terrain and where light or low wind speed conditions are likely to occur. CALPUFF is a non-steady state Lagrangian Gaussian puff model containing modules for complex terrain effects, overwater transport, coastal interaction effects, building downwash, wet and dry removal, and simple chemical transformation. In other words, t he model can simulate the effects of time- and space-varying meteorological conditions on pollutant transport, transformation and removal.

The modelling was set up and performed in accordance with EPA Tasmania's current Draft of Tasmanian Atmospheric Dispersion Modelling Guidelines V 0.93e (Draft) Last modified 29 January 2016 and the guidance contained the NSW OEH’s Generic Guidance and Optimum Model Settings for the CALPUFF Modeling System for Inclusion into the ‘Approved Methods for the Modeling and Assessments of Air Pollutants in NSW, Australia’ dated March 20112.

3.2 Meteorological Data and Model Run Period

Meteorological modelling for a full year period in 2015 has been conducted for Blackmans Bay WWTP. The year 2015 of meteorological data was chosen as it represents a recent year in a neutral El Nino year. The meteorological data set has been custom built to the Blackmans Bay site. The meteorological model has used hourly observational data from the Bureau of Meteorology’s four nearest meteorological stations which are Dennes Point, Hobart, Kunyani and Grove plus a single upper air station, Hobart Airport. Two models, the Australian CSIROs the Air Pollution Model (TAPM) and CALMET, the diagnostic meteorological component of the CALPUFF suite of models, were used to develop the meteorological data set at the WWTP. Both models are recognised as guideline models in Australia and New Zealand. Hourly observational data of temperature, wind speed, direction, relative humidity and pressure were obtained from all four of the meteorological stations.

As well as preparing a one year meteorological data set, an analysis has been conducted on two historic data sets that have been used in previous air modelling. The first is a December 2004 - December 2005 AUSPLUME prepared meteorological data set from monitored data at Blackmans Bay. The second is an AUSPLUME data set derived from TAPM data for 2006 which was used in odour modelling in 2014 (summarised in the CEE Odour Modelling Report , 2014). An evaluation of the monitored on-site data for 2005 suggests that the wind direction has been incorrectly reported in the AUSPLUME meteorological file and is 180 degrees out. This error was not picked up in the 2014 modelling and Blackmans Bay data was ruled as ‘unsuitable’ as the anemometer is located on a building and does not meet the Australian Wind monitoring standards. However, when the wind direction data is corrected the data appears good and acceptable for use in modelling. The second data set, the 2006 AUSPLUME data set developed from TAPM data at the Blackmans Bay site was used in the 2014 modelling. An in-depth analysis showed that the TAPM derived westerly flow dominated the daily cycle, even during the day when onshore sea breezes are common daily occurrence especially in summer.

1 Approved Methods for the Modelling and Assessment of Air Pollutants in New South Wales, Department of Environment

and Conservation NSW (DEC), NSW Environment Protection Authority (EPA), August, 2005 (the ‘Approved Methods’). 2 Generic Guidance and Optimum Model Settings for the CALPUFF Modeling System for Inclusion into the ‘Approved

Methods for the Modeling and Assessments of Air Pollutants in NSW, Australia, New South Wales Office of Environment and Heritage, Sydney Australia, March 2011.


The new 2015 data set has been exclusively developed from observation stations and Hobart Upper Air Data as TAPM either as gridded 3-dimensional data or individual profiles did not perform well. However, because Dennes Point is the closest location to the WWTP there is a tendency for the wind patterns to be similar to Dennes Point. This is a reasonable assumption given their close location.

Development of a meteorological data set at Blackmans Bay WWTP is highly complex due to t he large scale topographic features upwind, the effects of the Peninsula, the sea breeze and the local topography around the facility. It is highly recommended to reinstall a meteorological station at Blackmans Bay WWTP. Further, it is recommended that the 2005 on-site AUSPLUME meteorological data be corrected and then used directly in CALPUFF to provide robustness to the 2015 modelling.

A full report and detailed assessment is provided in Appendix C.

3.3 Dispersion Options

The NSW OEH’s generic guidance document on CALPUFF3 recommends that the model should be run using the turbulence-based dispersion coefficients rather than the US EPA default method, which uses the Pasquill-Gifford (PG) curves and ISC rural dispersion coefficients and McElroy-Pooler (MP) curves for urban dispersion coefficients (collectively known as the ‘PG /MP dispersion coefficients’).

In this assessment, MWH selected the turbulence-based dispersion coefficients option in CALPUFF, in accordance with OEH (2011) and the Approved Methods (OEH, 2005).4 Heights and dimensions of nearby buildings as input in the US EPA building wake program, BPIP, to account for the effect that building downwash has on plume dispersion from point source emissions. Buildings/structures included were the control building, centrifuge/sludge handling building, MCC/blower building, biotrickling filter and activated carbon vessels, and the existing anaerobic digester.

3.4 Terrain Elevations

The CALMET and CALPUFF models include terrain data sourced from the SRTM-3 digital elevation model (90 m resolution) data originally produced by NASA. The gridded data is representative of the local terrain within the modelling domain, and assists in simulating the effects of land surface elevations on plume dispersion and hence odour dispersion.

Figure 3-1 shows the area surrounding the project site, including the terrain input into CALPUFF and the discrete receptor layout (indicated with red crosses). Three sets of discrete receptor grids were used, varying from a coarse to a fine resolution. The 10 km x 10 km outer receptor grid has a resolution of 500 m, the second inner grid of 5 km x 5 km has a resolution of 250 m, and the innermost grid of receptors centred 2 km2 around the WWTP has a resolution of 100 m. A total of 1200 receptors were used.

3 New South Wales Office of Environment and Heritage (OEH), 2011. Generic Guidance and Optimum Model Settings for the

CALPUFF Modeling System for Inclusion into the ‘Approved Methods for the Modeling and Assessments of Air Pollutants in NSW, Australia, Sydney, Australia, March 2011.

4 Approved Methods for the Modelling and Assessment of Air Pollutants in New South Wales, Department of Environment and Conservation NSW (DEC), NSW Environment Protection Authority (EPA), August, 2005 (the ‘Approved Methods’).


Figure 3-1: Terrain elevations at the site and discrete receptor grids

3.5 Sensitive Receptors

In the context of this odour assessment, the term ‘sensitive receptor’ includes any persons, locations or systems that may be susceptible to changes in ambient odour concentrations as a consequence of discharges to air (i.e. odour) from the project site.

Typical locations for sensitive receptors include:

Residential properties;

Retirement villages;

Hospitals or medical centres;

Schools;

Libraries; and,

Public outdoor locations (e.g. parks, reserves, sports fields).

Table 3-1 presents a summary of the discrete receptors representing potential odour-sensitive locations surrounding Blackmans Bay WWTP, also shown in Figure 3-2.


Table 3-1: Sensitive receptor locations used in the modelling

Receptor ID

Description

Easting MGA

X (km)

Northing MGA

Y (km)

Elevation (m)

1 Rural property to the west of WWTP (within land identified to be purchased by TasWater) 526.587 5237.410 58.6

2 Rural property to the west of WWTP 526.446 5237.377 71.7

3 Rural property to the west of WWTP (nearest to the Scout hall) 526.407 5237.328 69.3

4 Residential property along Suncoast Drive, to the north of WWTP 526.598 5237.581 65.9



7 Rural property to the south west of WWTP 526.382 5236.966 98.0

Figure 3-2: Aerial base map showing the project site and sensitive receptor locations


Current TasWater land TasWater will purchase land from Council


4 Odour Assessment Criteria The Environment Protection Authority for Tasmania (EPA Tasmania) is the state’s independent

environmental regulator and was established under the Environmental Management and Pollution

Control Act 1994 (‘the Act’ or EMPCA). Under the powers of the Act, EPA Tasmania is responsible

for protecting the environment and the community through effective regulation of industry and

pollution, including odour discharges.

Impacts from odorous air contaminants are often nuisance-related rather than health-related. Odour performance goals guide decisions on odour management, but are generally not intended to achieve “no odour”. The detectability of an odour is a sensory property that refers to the theoretical minimum concentration that produces an olfactory response or sensation. This point is called the odour threshold and defines one odour unit (ou). An odour goal of less than 1 ou would theoretically result in no odour impact being experienced.

In practice, the character of a particular odour can only be judged by the rece iver’s reaction to it, and preferably only compared to another odour under similar social and regional conditions. Based on the literature available, the level at which an odour is perceived to be a nuisance can range significantly depending on a combination of the following factors:

Odour quality: whether an odour results from a pure compound or from a mixture of compounds. Pure compounds tend to have a higher threshold (lower offensiveness) than a mixture of compounds.

Population sensitivity: any given population contains individuals with a range of sensitivities to odour. The larger a population, the greater the number of sensitive individuals it may contain.

Background level: whether a given odour source, because of its location, is likely to contribute to a cumulative odour impact. In areas with more closely-located sources it may be necessary to apply a lower threshold to prevent offensive odour.

Public expectation: whether a given community is tolerant of a particular type of odour and does not find it offensive, even at relatively high concentrations. For example, background agricultural odours may not be considered offensive until a higher threshold is reached than for odours from a landfill facility.

Source characteristics: whether the odour is emitted from a stack (point source) or from an area (diffuse source). Generally, the components of point source emissions can be identified and treated more easily than diffuse sources. Emissions from point sources can be more easily controlled using control equipment. Point sources tend to be located in urban areas, while diffuse sources are more often located in rural locations.

Health Effects: whether a particular odour is likely to be associated with adverse health effects. In general, odours from agricultural activities are less likely to present a health risk than emissions from industrial facilities.

Experience gained through odour assessments from proposed and existing odour-generating facilities in Tasmania (including wastewater treatment plants) indicates that an odour performance goal of 2 ou is likely to represent the level below which an “offensive” odour should not occur (for an individual with a ‘standard sensitivity’ to odour).

In Schedule 3 of Environment Protection Policy (Air Qua lity) 2004 (‘the EPP’), the EPA Tasmania has recommended an odour threshold concentration (design criterion) of 2 ou, and no members of the public should be exposed to ambient odour concentrations above this criterion value. This criterion value is expressed as the 99.5th percentile and as a 1-hour mean concentration in effect at the site boundary. We have assumed this to mean the land within the restrictive easement area.

It is expected that an odour impact assessment criterion of 2 ou (expressed as the 99.5th percentile for a 1-hour mean concentration) would appropriately assess the odour performance of the project site.


5 Odour Impact Assessment Four scenarios were modelled to predict the odour impact of the new Blackmans Bay WWTP and one additional scenario was evaluated:

Scenario 1: Normal Operation of the New WWTP

Scenario 2: Inlet Works Maintenance Period for the New WWTP

Scenario 3: Upset in the Treatment Process for the New WWTP

Scenario 4: Upset in the Sludge Processing for the New WWTP

Scenario 5: Commissioning Activities with the New WWTP

5.1 Scenario 1 – Normal Operation of the New WWTP

Odour emissions from the new Blackmans Bay WWTP were modelled in CALPUFF to assess the predicted odour impact under normal operations.

5.1.1 Odour Emission Data and Assumptions

Odour emissions from the new Blackmans Bay WWTP were modelled in CALPUFF to assess the predicted odour impact under normal operations. The Scenario 1 odour emission sources are listed in Table B-1 in Appendix B, with covered / ventilated sources highlighted in blue. The odour sources presented are based on the following assumptions:

Odour source locations were based on the BAJV general arrangement site plan ‘G002-AA008274-P7’ provided by TYR Group and included in Appendix A. Surface areas for area sources were provided by TYR Group;

SOERs and odour concentrations were selected using the MWH odour emission database (refer Table 2-3). A constant emission rate was assumed for each odour source for the duration of the year, apart from the IDEA-SBR Aeration, Anoxic and Settling/Decant phases which assumed the following:

- An operating schedule comprising a 30 minute Anoxic phase, 1 hour 30 minutes Aerobic phase, and 2 hour Settling/Decant phase (provided by TYR Group). Due to the hourly-averaged model time-step, this was input in CALPUFF as 3 cycles of a 1 hour Anoxic; 3 hours Aerobic; and 4 hours Settling/Decant cycle across a 24 hour period.

- Time-variable scaling factors were applied to the SOERs for Aerobic/Anoxic/Settling phases listed in Table 5-4 and summary Table B-1.

The following process areas were modelled as covered, with forced extraction of foul air to the Biotrickling Filter Odour Control Facility (OCF):

- Inlet Works incl. the screenings handling, grit classifier and bins (95% cover capture)

- Flow Distribution Channel (99% cover capture)

- Inlet Works Return Pump Station (99% cover capture)

- Centrifuge and sludge transfer conveyors (not included in the model)

- Dewatered Cake Self-Loading Bin (99.9% capture)

The OCF is a two stage biotrickling filter / activated carbon system, modelled with an OER of 901 ou.m3/s and based on the following assumptions:

- an odour discharge concentration of 500 ou, equivalent to a two stage biotrickling filter with downstream activated carbon polishing

- an air flow of 6,586 m3/hr, based on air changes specified in the BAJV Basis of Design and extraction rates for covered process areas listed above

- a stack diameter of 0.391 m to achieve a 15 m/s exit velocity with the air flow above

- a stack height of 12 m to provide sufficient dispersion


Odour emissions from the chlorine contact tanks, thickened sludge pump station and centrifuges were not included in the model

The following tables detail the location and source parameters of all modelled point and area sources input in Scenario 1. A summary source input table for Scenario 1 can be found in Appendix B, along with source information for Scenarios 2-4.

The location of the point emission source at the Blackmans Bay WWTP is provided in Table 5-1 and shown in Figure 5-1.

Table 5-1: Point emission source locations

Source ID

Source Description

UTM Zone 55 S

Elevation (m) Easting

(km) Northing

(km)

BTFOCF Biotrickling Filter Odour Control Facility Stack 526.717 237.364 35.8

The odour emission rate in ou.m3/s for the wake-affected stack in Scenario 1 is provided in Table 5-2. The odour emission was assumed to be constant (i.e. 24 hours a day, 7 days a week) throughout the 1-year model run period.

Table 5-2: Odour emission data input into the model for point sources

Source ID

Source Description Stack Height

(m)

Stack Diameter

(m)

Stack Temperature

(K)

Exit Velocity

(m/s)

OER (ou.m3

/s)

BTFOCF

Biotrickling Filter Odour Control Facility Stack

12 0.391 298 15 901

The location of the 18 area emission sources which were input into the model are provided in Table 5-3.

Table 5-3: Area emission source locations

Source ID

Source Description

UTM Zone 55 S (SW Corner)

Elevation (m)

Easting (km)

Northing (km)

INWRKS Inlet Works (screenings handling, grit classifier, bins)

526.648 5237.356 48.5

FLWDST Flow Distribution Channel 526.683 5237.363 44.6

IWPUMP Inlet Works Return Pump Station 526.643 5237.357 49.8

GPPUMP General Purpose Pump Station (centrate return)

526.746 5237.425 32.7

1ANOX1 IDEA-SBR 1 Anoxic Selector Zone 526.685 5237.368 43.0

1ANOX2 IDEA-SBR 1 Secondary Anoxic Zone

526.666 5237.370 43.0

1AERAT IDEA-SBR 1 Aeration Phase 526.666 5237.382 43.0

1ANOX3 IDEA-SBR 1 Anoxic Phase 526.666 5237.382 43.0


Source ID

Source Description

UTM Zone 55 S (SW Corner)

Elevation (m)

Easting (km)

Northing (km)

1DECAN IDEA-SBR 1 Settling / Decant Phase

526.666 5237.382 43.0

2ANOX1 IDEA-SBR 2 Anoxic Selector Zone 526.684 5237.349 44.6


526.665 5237.350 44.6

2AERAT IDEA-SBR 2 Aeration Phase 526.663 5237.305 44.6

2ANOX3 IDEA-SBR 2 Anoxic Phase 526.663 5237.305 44.6


526.663 5237.305 44.6

GRAVTH Gravity Thickener 526.753 5237.406 29.6

DIGAER Aerobic Digester - Aerobic Cells 526.758 5237.367 25.1

DIGANO Aerobic Digester - Anoxic Cells 526.751 5237.356 27.1

SPIROT Dewatered Cake Self-Loading Bins 526.736 5237.416 33.8

The specific odour emission rates (ou.m/s) for the area sources input in Scenario 1 are provided in Table 5-4. The odour emissions were assumed to be constant (i.e. 24 hours a day, 7 days a week) throughout the run period, apart from the IDEA-SBR Aeration, Anoxic and Settling/Decant phases (described above).

Table 5-4: Odour emission data input into the model for area sources

Source ID

Source Description Source

Area (m2)

Release Height

(m)

Initial Sigma z

(m)

SOER (ou.m/s)


72 1.9 1

0.224

FLWDST Flow Distribution Channel 24 2.9 1 0.045

IWPUMP Inlet Works Return Pump Station 4 0.0 1 0.045


7 0.0 1

4.470

1ANOX1 IDEA-SBR 1 Anoxic Selector Zone

58 2.4 1

1.700


192 2.4 1

0.695

1AERAT IDEA-SBR 1 Aeration Phase

1,062

2.4 1 0.313

1ANOX3 IDEA-SBR 1 Anoxic Phase 2.4 1 0.695


2.4 1

0.076


58 2.4 1

1.700


192 2.4 1

0.695


Source ID


Area (m2)

Release Height

(m)

Initial Sigma z

(m)

SOER (ou.m/s)


1,062

2.4 1 0.313

2ANOX3 IDEA-SBR 2 Anoxic Phase 2.4 1 0.695


2.4 1

0.076

GRAVTH Gravity Thickener 177 0.0 1 0.200

DIGAER Aerobic Digester - Aerobic Cells 169 0.0 1 0.150

DIGANO Aerobic Digester - Anoxic Cells 169 0.0 1 0.300

SPIROT Dewatered Cake Self-Loading Bins

23 1.5 1

0.029

The location of the Scenario 1 emission sources and buildings is shown in Figure 5-1, using the source ID referred to in Table 5-1 and Table 5-3. The existing (red line) and future (blue line) site boundaries are also shown.

Figure 5-1: Aerial image showing the emission source locations for Scenario 1

5.1.2 Modelling Results

Figure 5-2 presents a dispersion plot of the predicted odour impact of the new Blackmans Bay WWTP under normal operation (Scenario 1). The white contour line indicates the EPA Tasmania 2 ou, 99.5th percentile assessment criteria for Scenario 1.

The model predicts that the odour impact of the new WWTP does not exceed the 2 ou, 99.5th percentile criteria at or beyond the future site boundary indicated in the plot (a combination of current



TasWater land and land which may be purchased from Council). Based on the model inputs and assumptions listed in this report, and assuming the site boundary is extended to the west and south of the existing WWTP as indicated in the figure, Scenario 1 complies with the EPA Tasmania odour criteria.

Figure 5-2: Blackmans Bay Scenario 1 odour concentration contour plot

5.2 Scenario 2 – Inlet Works Maintenance Period for the New WWTP

Odour emissions from the new Blackmans Bay WWTP were modelled in CALPUFF to assess the predicted odour impact during scheduled maintenance at the inlet works.

5.3 Odour Emission Data and Assumptions

The Scenario 2 odour emission sources are listed in Table C-2 in Appendix B with covered / ventilated sources highlighted in blue. The odour sources presented are the same as those presented for Scenario 1 with the exception of the following:


An increase in odour emissions from the inlet works by 100% to represent a period of scheduled maintenance at the inlet works i.e. the SOER was doubled for the inlet works, flow distribution channel, inlet works return pump station and general purpose pump station.


Figure 5-3 presents a dispersion plot of the predicted odour impact of the new Blackmans Bay WWTP under inlet works maintenance conditions (Scenario 2). The yellow contour line indicates the EPA Tasmania 2 ou, 99.5th percentile assessment criteria for Scenario 2. The Scenario 1 white contour is also shown for reference.

Such an increase in emission rates would result in the removal of a proportion of covers, resulting in loss of negative pressure and thus containment. Even so, the resulting footprint is not significantly different to the base case.

If total cover removal was required (to respond to a major maintenance or failure issue), which would increase emissions further, the emissions could be mitigated by increasing the magnesium hydroxide chemical dose into the network, raising the incoming pH to 8.8 to 9.

The model predicts that the odour impact of the new WWTP under inlet works maintenance conditions does not exceed the 2 ou, 99.5th percentile criteria at or beyond the future site boundary indicated in the plot (a combination of current TasWater land and land to be purchased from Council). Based on the model inputs and assumptions listed in this report, and assuming the site boundary is extended to the west and south of the existing WWTP as indicated in the figure, Scenario 2 complies with the EPA Tasmania odour criteria.



5.4 Scenario 3 – Upset in the Treatment Process for the New

WWTP

Odour emissions from the new Blackmans Bay WWTP were modelled in CALPUFF to assess the predicted odour impact under treatment process upset conditions.


The Scenario 3 odour emission sources are listed in Table B-3 in Appendix B, with covered / ventilated sources highlighted in blue. The odour sources presented are the same as those presented for Scenario 1 with the exception of the following:

An increase in odour emissions from all process tanks by 100% to represent treatment process upset conditions i.e. the SOER was doubled for the inlet works, flow distribution channel, inlet


works return pump station, general purpose pump station, secondary treatment IDEA-SBR tanks, gravity thickener, and aerobic digester.

5.5 Modelling Results

Figure 5-4 presents a dispersion plot of the predicted odour impact of the new Blackmans Bay WWTP under treatment process upset conditions (Scenario 3). The red contour line indicates the EPA Tasmania 2 ou, 99.5th percentile assessment criteria for Scenario 3. The Scenario 1 white contour is also shown for reference.

The model predicts that the odour impact of the new WWTP under treatment process upset conditions exceeds the 2 ou, 99.5th percentile criteria at the existing site boundary (red dotted line) and the extended, future boundary (blue dotted line) as a result of TasWater’s purchase of land from Council.

Scenario 3 does not comply with the EPA Tasmania odour criteria, however it is not considered to be a realistic failure mode of the facility, and is highly unlikely to occur. It should be considered to be an “absolute worst possible” scenario. The following should be noted;

1. Issues in sewage processing which effect odour emissions across the entire treatment process from the inlet works to the secondary treatment process are generally limited to an unauthorised industrial type discharge of an organic low volatility material. Such a discharge cannot be predicted, and in any case, would generally only be of significant magnitude to effect part of the process rather than all process units at the same time.

2. It should be noted that this scenario has been modelled as if a process upset impacting the process units listed above occurs throughout the entire year (with the impact shown being the 99.5 percentile impact). This is not a realistic occurrence. Such a catastrophic process upset would only occur for a short period (hours or days) which is not reflected in this model output. The process upset would have to occur consistently during times of poor meteorological impact and at times when sensitive populations are within the small impacted area for an odour complaint to occur, which is considered a highly unlikely event.

3. The only liquid stream impacts which have a possibility of occurring are;

a. A “washout” resulting in reduced sludge age. Reducing the sludge age by 5 days would increase the aeration phase emissions by approximately 20% to 25%, which would not exceed the EPA criteria

b. Failure of one or more of the aeration grids resulting in anoxic conditions in part of the SBR during aeration. This would result in a doubling of the emission for that part of the cell for the duration of the aeration phase. This would not exceed the EPA criteria.



5.6 Scenario 4 – Upset in the Sludge Processing for the New WWTP

Odour emissions from the new Blackmans Bay WWTP were modelled in CALPUFF to assess the predicted odour impact under sludge processing upset conditions.


The Scenario 4 odour emission sources are listed in Table B-4 in Appendix B, with covered / ventilated sources highlighted in blue. The odour sources presented are the same as those presented for Scenario 1 with the exception of the following:

An increase in odour emissions from areas surrounding the centrifuge building by 100% to represent sludge processing upset conditions i.e. the SOER was doubled for the dewatered


cake self-loading bin. Note that emissions from the centrifuges building were not included in the model (refer Table 2-2).


Figure 5-5 presents a dispersion plot of the predicted odour impact of the new Blackmans Bay WWTP under sludge processing upset conditions (Scenario 4). The orange contour line indicates the EPA Tasmania 2 ou, 99.5th percentile assessment criteria for Scenario 4. The Scenario 1 white contour is also shown for reference.

The model predicts that the odour impact of the new WWTP under sludge processing upset conditions does not exceed the 2 ou, 99.5th percentile criteria at or beyond the future site boundary indicated in the plot (a combination of current TasWater land and land to be purchased from Council). Based on the model inputs and assumptions listed in this report, and assuming the site boundary is extended to the west and south of the existing WWTP as indicated in the figure, Scenario 4 complies with the EPA Tasmania odour criteria.



5.7 Scenario 5: Commissioning Works

An assessment of the predicted impact of odour emissions from the new Blackmans Bay WWTP during its commissioning phase was undertaken using odour emission data.


The commissioning activities are anticipated to include the following methodology:

1. The existing primary clarifiers, bioreactor and secondary clarifier out of service as IDEA-SBR reactor 1 is used as a liquid stream process

2. The second reactor (IDEA-SBR 2) will be used as an aerobic digester during this period (while the existing bioreactor is converted to an aerobic digester).

The specific odour emission rates (ou.m/s) for the area sources estimated for Scenario 5 are shown in Table 5-5. Those for Scenario 1 are also shown for comparison. The odour emissions were assumed to be constant (i.e. 24 hours a day, 7 days a week) throughout the run period, apart from the IDEA-SBR Aeration, Anoxic and Settling/Decant phases (refer Section 5.1.1)

The specific odour emission rates for point sources are as per Scenario 1 in Section 5.1.1.

Table 5-5: Odour emission data for area sources in Scenario 1 and Scenario 5

Source ID


Area (m2)

Release Height

(m)

Initial Sigma z (m)

SOER (ou.m/s)

Scenario 1

Scenario 5


72 1.9 1

0.224 0.224

FLWDST Flow Distribution Channel

24 2.9 1

0.045 0.045

IWPUMP Inlet Works Return Pump Station

4 0.0 1

0.045 0.045


7 0.0 1

4.470 4.470


58 2.4 1

1.700 1.700


192 2.4 1

0.695 0.695


1,062

2.4 1

0.313 0.313

1ANOX3 IDEA-SBR 1 Anoxic Phase

2.4 1

0.695 0.695


2.4 1

0.076 0.076


58 2.4 1

1.700 0.313


192 2.4 1

0.695 0.313


1,062 2.4 1

0.313 0.313


Source ID


Area (m2)

Release Height

(m)

Initial Sigma z (m)

SOER (ou.m/s)

Scenario 1

Scenario 5

2ANOX3 IDEA-SBR 2 Anoxic Phase

2.4 1

0.695 0.313


2.4 1

0.076 0.313

GRAVTH Gravity Thickener 177 0.0 1 0.200 0.200

DIGAER Aerobic Digester - Aerobic Cells

169 0.0 1

0.150 -

DIGANO Aerobic Digester - Anoxic Cells

169 0.0 1

0.300 -

SPIROT Dewatered Cake Self-Loading Bins

23 1.5 1

0.029 -

5.7.2 Assessment Results

The assessment of odour emission rates in Table 5-5 demonstrates that the emission rates for Scenario 5 are far less than for Scenario 1, which is shown in Figure 5-2 to comply with the 2 ou, 99.5 percentile criteria outside the future site boundary. CALPUFF modelling was therefore not conducted for Scenario 5 as it is not anticipated to have an impact outside the future site boundary (a combination of current TasWater land and land which may be purchased from Council).


6 Odour Assessment Summary

6.1 Predicted Odour Concentrations at Sensitive Receptors

Table 6-1 presents a summary of the predicted odour impacts at the discrete receptors representing odour-sensitive locations surrounding Blackmans Bay WWTP. Predicted 1-hour average 99.5 percentile odour concentrations for Scenarios 1-4 have been recorded to two decimal places for comparison purposes only. Receptors 1, 2 and 3 represent the nearest rural residential properties to the west of the facility, receptors 4, 5 and 6 are arbitrary points along Suncoast Drive to show the predicted odour impact at residences to the north of the facility, and receptor 7 represents the nearest rural residential property to the south west. Figure 3-2 displays the discrete receptor locations. The predicted 99.5 percentile odour concentrations in Scenario 1 (normal operations of the new WWTP) did not exceed the EPA Tasmania 2 ou odour criterion at any of the sensitive receptor locations. Even under upset or maintenance conditions (Scenarios 2-4), the 99.5 percentile 2 ou criterion was not exceeded at these locations.

Table 6-1: Predicted 1-hour average, 99.5 percentile odour concentrations (ou) at sensitive receptors for Scenarios 1-4

Receptor ID

Easting MGA

X (km)

Northing MGA

Y (km)

Elevation (m)

Predicted 1hr average, 99.5 percentile odour concentration (ou)

Scenario 1 Scenario 2 Scenario 3 Scenario 4

1 526.587 5237.410 58.6 0.67 0.70 1.32 0.67

2 526.446 5237.377 71.7 0.30 0.31 0.54 0.30

3 526.407 5237.328 69.3 0.29 0.29 0.46 0.29

4 526.598 5237.581 65.9 0.46 0.48 0.87 0.46

5 526.677 5237.631 60.2 0.52 0.54 1.01 0.52

6 526.779 5237.651 46.8 0.55 0.57 1.09 0.55

7 526.382 5236.966 98.0 0.17 0.17 0.28 0.17

The predicted 100 percentile (maximum) odour concentrations for Scenarios 1-4 provided in Table 6-2 also did not exceed the EPA Tasmania 2 ou odour criterion at the identified sensitive receptors, apart from Receptor 1 in Scenario 3 with a concentration of 3.6 ou. However as discussed in Section 5.5 process upset conditions modelled throughout the year in Scenario 3 are not realistic and highly unlikely to occur.


Table 6-2: Predicted 1-hour average, 100 percentile odour concentrations (ou) at sensitive receptors for Scenarios 1-4

Receptor ID

Easting MGA

X (km)

Northing MGA

Y (km)

Elevation (m)

Predicted 1hr average, 100th percentile odour concentration (ou)

Scenario 1 Scenario 2 Scenario 3 Scenario 4

1 526.587 5237.410 58.6 1.84 1.88 3.56 1.84

2 526.446 5237.377 71.7 0.88 0.89 1.67 0.88

3 526.407 5237.328 69.3 0.76 0.77 1.42 0.76

4 526.598 5237.581 65.9 0.83 0.84 1.53 0.83

5 526.677 5237.631 60.2 0.89 0.89 1.66 0.89

6 526.779 5237.651 46.8 0.83 0.85 1.67 0.83

7 526.382 5236.966 98.0 0.40 0.41 0.76 0.40

Table 6-1 and Table 6-2 indicate that for each modelling scenario the highest 1-hour mean (as 99.5th

and 100th percentile) concentration is predicted at sensitive receptor 1. However the location of this

receptor lies within the future site boundary, meaning it is on land to be purchased by TasWater.

6.2 Time of Day Impacts

Modelling did not show any off-site impact for any of the scenarios likely to eventuate. As none of the sensitive receptors were in exceedance of the impact criteria, time of day impacts were not investigated further.

6.3 Management of Odour Impact during Adverse Weather Conditions

MWH have taken the term ‘adverse weather conditions’ to mean the management of storm flows. During storm flows, the retention time within the sewer decreases and wastewater tends to become more dilute, reducing the potential for odour impact.

However the first flush of storm water can deposit into the inlet works any silted sludge accumulated within the network which has the potential of being septic. This can lead to short times of higher than anticipated odour emitted from the inlet works. For a plant the size of Blackmans Bay WWTP, this rarely effects plant downstream of the inlet works.

6.4 Management of odour during biosolids export

Biosolids export has historically been an odour problem for many sites, as there is generally a sudden release of reduced sulphur compounds during outloading events. The action of conveyors and disturbance of sludge (which has turned anaerobic) during the transfer of sludge from the onsite storage hopper to a waiting truck can have significant off-site impact.

To mitigate this, the design utilizes self-loading enclosed sprotainer type bins. These are filled on demand from the centrifuges via enclosed conveyors. The spirotainers, and conveyors are ventilated at a high rate to contain odour, and the sludge is not exposed to atmosphere during its removal from


site. Odour produced from the dewatered biosolids will be contained at all times, both during on-site storage, and during its removal from site.

Odour nuisance caused by outloading events is not envisaged with this design.

6.5 Management of odour during construction

A detailed odour mitigation plan shall be produced for the construction phase of the project when the detailed construction methodology is interrogated. The odour mitigation plan will include, but not be limited too;

1. Network dosing to reduce site gas levels and potential for odour nuisance.

2. Consideration of maintaining existing odour control systems in operation as long as practicable during the construction / new plant commissioning phases to a llow for treatment of odour, or the provision of temporary odour control facilities.

3. Regular re-balancing and surveillance of odour control systems during the construction

period to ensure continued satisfactory operation.

4. Odour prevention, reduction and containment being a requirement in SWMS and operational plans during the construction period.

5. The prompt removal of sewage products and cleaning of vessels which are being

decommissioned or re-purposed.

6. The use of atomization sprays (if required) during the de-gritting and removal of products from the digester.

7. No storage of Odorous products on site, and removal from site in a timely manner

8. Phased startup of the plant to enable the new odour control facilities to acclimatize, and use

of the downstream carbon during this period to prevent odorous gas discharge.

7 Summary and Conclusions The CALPUFF dispersion model was used to assess the predicted odour impact of the new Blackmans Bay WWTP under normal operating conditions and plant upset conditions against EPA Tasmania’s 2 ou, 99.5th percentile, 1-hour average odour impact assessment criteria. Suitable odour emission data was selected from the MWH Global Database and CALMET meteorological modelling was undertaken using surface observational data from Hobart, Dennes Point, Grove and Kunyani and upper air data from Hobart

The modelling found that the predicted odour impact of the new Blackmans Bay WWTP:

Did not exceed EPA Tasmania requirements beyond the future site boundary (assuming TasWater purchases land to the west and south of the existing WWTP boundary) when modelled under normal operating conditions (Scenario 1);

Did not exceed EPA Tasmania requirements beyond the future site boundary (assuming TasWater purchases land to the west and south of the existing WWTP boundary) when modelled during scheduled maintenance at the inlet works resulting in an increase in odour emissions from the inlet works by 100% (Scenario 2);


Exceeded EPA Tasmania requirements beyond the future site boundary (to the south of the existing WWTP boundary) when under treatment process upset conditions resulting in an increase in odour emissions from all process tanks by 100% (Scenario 3), however this is not considered to be a realistic scenario. As previously discussed, realistic scenarios resulting in increases in liquid stream emissions are unlikely to exceed EPA Tasmania requirements; and

Did not exceed EPA Tasmania requirements beyond the future site boundary (assuming TasWater purchases land to the west and south of the existing WWTP boundary) when modelled under sludge processing upset conditions resulting in an increase in odour emissions from the dewatered cake self-loading bin by 100% (Scenario 4).

Is likely to not exceed EPA Tasmania requirements beyond the future site boundary (assuming TasWater purchases land to the west and south of the existing WWTP boundary) when modelled under commissioning conditions, with commissioning activities as listed in Scenario 5.

It should be noted that emission rates were estimated / derived by MWH utilising the MWH emissions database. Whilst this historically produces datasets within 10% of measured emissions, there is a risk that odour emissions may be higher or lower than estimated and a resulting risk of odour impacts. It is recommended that TasWater verify the odour emission rates and capture efficiencies of covered process units when the site is operational to validate the odour modelling.

83503021-P-002 Blackmans Bay Odour Impact Assessment Report_Rev C

Appendix A Tender Design Site Layout Drawing

525Ø

525Ø

525Ø

525Ø

0 5 10 15 20

1:500 at A1

References

Datum

C

disclosed to third parties, or copied or reproduced whollyremains the property of TasWater and must not beThis drawing and the information it contains is, and

Sheet NumberTASMANIAN WATER & SEWAGE CORPORATION PTY LTD

DRAWING ISSUE

or in part or in any format without the written consentof the owners. The information contained herein is also

Project No

PROJECT DETAILS

Scale

ABN: 47 162220 653

REVISION

Sheet Size

Vault Folder

HPRM File Ref.

Discipline

DESIGN

Drawn

DATE

Designed

Verified

This drawing is produced on an A3 size sheet,DO NOT SCALE a sheet plotted at any other size.

21 3 4 5 6

21 3 4 5 6

G

A

C

D

E

F

H

B

G

A

C

D

E

F

H

B

correct and up-to-date, but all details should be verifiedon site by the user prior to construction.

Rev. ApprovedDate

Revision Notes KINGBOROUGH SEWERAGE PROJECTBBT1-BLACKMANS BAY SEWAGE TREATMENT PLANT

GENERAL ARRANGMENTSITE PLAN

J.15950

PROJECTS

FSW11/378

P

AM 03.11.15

DF 03.11.15

NS 15.12.15

-

1:500AHD (Tas.)A3

15.12.15 NS J15950-STP-G-1012015-

FOR TENDER


Appendix B Odour Source Model Input Tables


Table B-1: Odour sources in Scenario 1 - Normal Operations of New WWTP


ID

Source

Type

Surface Area

Base Elevation

note1

Effective Release

Height note2

Estimated SOER

note3

Covered / Extracted

From

Capture Rate note4

Modelled SOER

note5

OER note6

(m2) (m) (m) (ou.m/s) (ou.m/s) (ou.m3/s)


INWRKS Area 72 48.5 1.9 4.47 Y 95% 0.224 16

Flow Distribution Channel FLWDST Area 24 44.6 2.9 4.47 Y 99% 0.045 1

Inlet Works Return Pump Station IWPUMP Area 4 49.8 0.0 4.47 Y 99% 0.045 0.2

General Purpose Pump Station (centrate return)

GPPUMP Area 7 32.7 0.0 4.47 N 0% 4.470 32

IDEA-SBR 1 Anoxic Selector Zone 1ANOX1 Area 58 43.0 2.4 1.70 N 0% 1.700 99


1ANOX2 Area 192 43.0 2.4 0.695 N 0% 0.695 133

IDEA-SBR 1 Aeration Phase 1AERAT Area

1,062

43.0 2.4 0.313 N 0% 0.313

time-variable emission

IDEA-SBR 1 Anoxic Phase 1ANOX3 Area 43.0 2.4 0.695 N 0% 0.695

IDEA-SBR 1 Settling / Decant Phase 1DECAN Area 43.0 2.4 0.076 N 0% 0.076

IDEA-SBR 2 Anoxic Selector Zone 2ANOX1 Area 58 44.6 2.4 1.70 N 0% 1.700 99


2ANOX2 Area 192 44.6 2.4 0.695 N 0% 0.695 133


1,062

44.6 2.4 0.313 N 0% 0.313


IDEA-SBR 2 Anoxic Phase 2ANOX3 Area 44.6 2.4 0.695 N 0% 0.695

IDEA-SBR 2 Settling / Decant Phase 2DECAN Area 44.6 2.4 0.076 N 0% 0.076

Gravity Thickener GRAVTH Area 177 29.6 0.0 0.20 N 0% 0.200 35

Aerobic Digester - Aerobic Cells DIGAER Area 169 25.1 0.0 0.15 N 0% 0.150 25

Aerobic Digester - Anoxic Cells DIGANO Area 169 27.1 0.0 0.30 N 0% 0.300 51



ID

Source

Type

Surface Area

Base Elevation

note1

Effective Release

Height note2

Estimated SOER

note3 Covered / Extracted

From

Capture Rate note4

Modelled SOER

note5

OER note6

(m2) (m) (m) (ou.m/s) (ou.m/s) (ou.m3/s)

Dewatered Cake Self-Loading Bins SPIROT Area 23 33.8 1.5 29.38 Y 99.9% 0.029 0.7

Odour Control Facility Stack BTFOCF Point n/a 35.8 12 n/a n/a n/a n/a 901

Note 1: Elevations sourced from SRTM3 terrain data

Note 2: Above ground level, taken from drawings and information provided by TYR Group Note 3: Estimated SOER = specific odour emission rate (taken from MWH database)

Note 4: Percentage of emissions captured by odour covers or contained in a building/structure

Note 5: Modelled SOER = specific odour emission rate (used in model) = estimated SOER x (1-(capture rate/100))

Note 6: OER = odour emission rate = modelled SOER x surface area (area sources); or volumetric air flow x odour concentration (volume/point sources)

Table B-2: Odour sources in Scenario 2 - Inlet Works Maintenance Period for New WWTP


ID

Source

Type

Surface Area

Base Elevation

note1

Effective Release

Height note2

Estimated SOER

note3

Inlet Works Maintenance SOER note3

Covered / Extracted

From

Capture Rate note4

Modelled SOER

note5

OER note6

(m2) (m) (m) (ou.m/s) (ou.m/s) (ou.m/s) (ou.m3/s)


INWRKS Area 72 48.5 1.9 4.47 8.94 Y 95% 0.447 32

Flow Distribution Channel FLWDST Area 24 44.6 2.9 4.47 8.94 Y 99% 0.089 2

Inlet Works Return Pump Station IWPUMP Area 4 49.8 0.0 4.47 8.94 Y 99% 0.089 0.3


GPPUMP Area 7 32.7 0.0 4.47 8.94 N 0% 8.940 63

IDEA-SBR 1 Anoxic Selector Zone 1ANOX1 Area 58 43.0 2.4 1.70 n/a N 0% 1.700 99


1ANOX2 Area 192 43.0 2.4 0.695

n/a N 0% 0.695 133


1,062

43.0 2.4 0.313 n/a N 0% 0.313


IDEA-SBR 1 Anoxic Phase 1ANOX3 Area 43.0 2.4 0.695 n/a N 0% 0.695

IDEA-SBR 1 Settling / Decant Phase 1DECAN Area 43.0 2.4 0.076 n/a N 0% 0.076



2ANOX2 Area 192 44.6 2.4 0.695

n/a N 0% 0.695 133


1,062

44.6 2.4 0.313 n/a N 0% 0.313




Gravity Thickener GRAVTH Area 177 29.6 0.0 0.20 n/a N 0% 0.200 35

Aerobic Digester - Aerobic Cells DIGAER Area 169 25.1 0.0 0.15 n/a N 0% 0.150 25

Aerobic Digester - Anoxic Cells DIGANO Area 169 27.1 0.0 0.30 n/a N 0% 0.300 51

Dewatered Cake Self-Loading Bins SPIROT Area 23 33.8 1.5 29.38 n/a Y 99.9% 0.029 0.7

Odour Control Facility Stack BTFOCF Point n/a 35.8 12 n/a n/a n/a n/a n/a 901






Note 6: OER = odour emission rate = modelled SOER x surface area (area sources); or volumetric air flow x odour concentration (volu me/point sources)


Table B-3: Odour sources in Scenario 3 - Treatment Process Upset for New WWTP


ID

Source

Type

Surface Area

Base Elevation

note1

Effective Release

Height note2

Estimated SOER

note3

Process Upset

SOER note3

Covered / Extracted

From

Capture Rate note4

Modelled SOER

note5

OER note6



INWRKS Area 72 48.5 1.9 4.47 8.94 Y 95% 0.447 32

Flow Distribution Channel FLWDST Area 24 44.6 2.9 4.47 8.94 Y 99% 0.089 2

Inlet Works Return Pump Station IWPUMP Area 4 49.8 0.0 4.47 8.94 Y 99% 0.089 0.3


GPPUMP Area 7 32.7 0.0 4.47 8.94 N 0% 8.940 63

IDEA-SBR 1 Anoxic Selector Zone 1ANOX1 Area 58 43.0 2.4 1.70 3.40 N 0% 3.400 197


1ANOX2 Area 192 43.0 2.4 0.695

1.39 N 0% 1.390 267


1,062

43.0 2.4 0.313 0.63 N 0% 0.626 time-

variable emission

IDEA-SBR 1 Anoxic Phase 1ANOX3 Area 43.0 2.4 0.695 1.39 N 0% 1.390

IDEA-SBR 1 Settling / Decant Phase 1DECAN Area 43.0 2.4 0.076 0.15 N 0% 0.152

IDEA-SBR 2 Anoxic Selector Zone 2ANOX1 Area 58 44.6 2.4 1.70 3.40 N 0% 3.400 197


2ANOX2 Area 192 44.6 2.4 0.695

1.39 N 0% 1.390 267


1,062

44.6 2.4 0.313 0.63 N 0% 0.626 time-

variable emission

IDEA-SBR 2 Anoxic Phase 2ANOX3 Area 44.6 2.4 0.695 1.39 N 0% 1.390

IDEA-SBR 2 Settling / Decant Phase 2DECAN Area 44.6 2.4 0.076 0.15 N 0% 0.152

Gravity Thickener GRAVTH Area 177 29.6 0.0 0.20 0.40 N 0% 0.400 71

Aerobic Digester - Aerobic Cells DIGAER Area 169 25.1 0.0 0.15 0.30 N 0% 0.300 51

Aerobic Digester - Anoxic Cells DIGANO Area 169 27.1 0.0 0.30 0.60 N 0% 0.600 101

Dewatered Cake Self-Loading Bins SPIROT Area 23 33.8 1.5 29.38 n/a Y 99.9% 0.029 0.7



Table B-4: Odour sources in Scenario 4 - Sludge Processing Upset for New WWTP


ID

Source

Type

Surface Area

Base Elevation

note1

Effective Release

Height note2

Estimated SOER

note3

Sludge Upset

SOER note3

Covered / Extracted

From

Capture Rate note4

Modelled SOER

note5

OER note6



INWRKS Area 72 48.5 1.9 4.47 n/a Y 95% 0.224 16

Flow Distribution Channel FLWDST Area 24 44.6 2.9 4.47 n/a Y 99% 0.045 1

Inlet Works Return Pump Station IWPUMP Area 4 49.8 0.0 4.47 n/a Y 99% 0.045 0.2


GPPUMP Area 7 32.7 0.0 4.47 n/a N 0% 4.470 32



1ANOX2 Area 192 43.0 2.4 0.695 n/a N 0% 0.695 133


1,062

43.0 2.4 0.313 n/a N 0% 0.313 time-

variable emission





2ANOX2 Area 192 44.6 2.4 0.695 n/a N 0% 0.695 133


1,062

44.6 2.4 0.313 n/a N 0% 0.313 time-

variable emission



Gravity Thickener GRAVTH Area 177 29.6 0.0 0.20 n/a N 0% 0.200 35

Aerobic Digester - Aerobic Cells DIGAER Area 169 25.1 0.0 0.15 n/a N 0% 0.150 25

Aerobic Digester - Anoxic Cells DIGANO Area 169 27.1 0.0 0.30 n/a N 0% 0.300 51

Dewatered Cake Self-Loading Bins SPIROT Area 23 33.8 1.5 29.38 58.76 Y 99.9% 0.059 1.3


Appendix C Input Meteorological Data Report

Development of a Meteorological

Modelling Data Set for Blackmans

Bay Wastewater Treatment Plant,

Tasmania

July 2016

Prepared For:

TYR Group on behalf of TasWater

Hobart

Tasmania

Prepared By:

J J Barclay

Independent Consultant, Atmospheric Sciences

678 Remuera Road, Remuera,

Auckland, 1050

Reviewed and amended by:

David Fligelman, Tyr Group, July 2016

TYR GROUP BLACKMANS BAY STP – METEOROLOGICAL MODELLING

J Barclay, Ind Consultant,Atmospheric Sciences Page 1

Contents

1 INTRODUCTION ............................................................................................................................ 4 1.1 BACKGROUND .................................................................................................................................... 4 1.2 PURPOSE OF THIS REPORT ..................................................................................................................... 4

1.2.1 Other relevant reports and Data ................................................................................................ 4 1.3 SCOPE OF REPORT ............................................................................................................................... 4

2 SITE DESCRIPTION AND HISTORIC DATA ANALYSIS ........................................................................ 6 2.1 LOCATION .......................................................................................................................................... 6 2.2 HISTORIC DATA ANALYSIS ..................................................................................................................... 6 2.3 METEOROLOGY OF BLACKMANS BAY ...................................................................................................... 8

3 METEOROLOGICAL MODELLING .................................................................................................. 11 3.1 CALPUFF SUITE OF MODELS .............................................................................................................. 11

3.1.1 Model Inputs ............................................................................................................................. 11 3.2 LAND USE AND TERRAIN ..................................................................................................................... 12

4 CALMET OUTPUT ........................................................................................................................ 15 4.1 WIND SPEED AND DIRECTION .............................................................................................................. 15 4.2 REPRESENTATIVE YEAR ....................................................................................................................... 19 4.3 CALMET – GENERATED SPATIAL WIND FIELDS ...................................................................................... 19 4.4 UPPER AIR DATA ............................................................................................................................... 19

5 CONCLUSIONS ............................................................................................................................ 22

6 ATTACHMENT A – WIND ROSES FROM DEC 2004 – DEC 2005 BLACKMANS BAY ............................ 23

7 ATTACHMENT B – WIND ROSES FOR TAPM DERIVED AUSPLUME 2006 DATA AS IN 2014 MODELLING ....................................................................................................................................... 24

8 ATTACHMENT C – TIME OF DAY WIND ROSES AT SURFACE OBSERVATION SITES AS USED IN THE 2015, CURRENT MODELLING ............................................................................................................... 26

9 ATTACHMENT D TAPM EVALUATION .......................................................................................... 31 9.1 METEOROLOGICAL EVALUATION .......................................................................................................... 31

10 ATTACHMENT E METEOROLOGY AT BLACKMANS BAY ................................................................. 33 10.1 CALMET OUTPUT ............................................................................................................................... 33



LIST OF FIGURES

Figure 2-1: Blackmans Bay Wastewater Treatment Plant. ................................................................ 6

Figure 2-2: Annual wind roses as displayed in the 2014 CEE report. ............................................... 7

Figure 2-3: Corrected 2005 Blackmans Bay Annual wind rose on left hand side with 2006 data used

in the modelling by CEE in 2014. ...................................................................................................... 8

Figure 2-4: Corrected 2005 Blackmans Bay wind roses. Wind is ‘blowing from’. ......................... 10

Figure 3-1: Terrain Map showing the local and regional features. .................................................. 13

Figure 3-2: Land use and terrain contours. ...................................................................................... 14

Figure 4-1: Annual, Seasonal and time of day Wind Roses from the Wiri Meteorological site, 2010.

.......................................................................................................................................................... 17

Figure 4-2: Chart plot showing the quantity and times of Hobart Radiosonde in 2015, UTC time. 20

Figure 4-3: Base Map showing the CALMET meteorological modelling domain (coloured area) with

terrain contours for 2015 modelling. ................................................................................................ 21

Figure 8-1: Annual, Seasonal and Time of day Wind Roses from Hobart, Dennes Point, Grove and

Kunyani for 2015. ............................................................................................................................ 26

Figure 10-1: CALMET stability classes at Blackmans Bay STP for the year 2015. ....................... 33

Figure 10-2: CALMET short wave radiation (W/m2) at Blackmans Bay STP for the year 2015. .. 34

Figure 10-3: CALMET mixing height (m) at Blackmans Bay STP for the year 2015. ................... 35

Figure 10-4: CALMET temperature (K) at Blackmans Bay STP for the year 2015. ...................... 36

Figure 10-5: CALMET wind speed (m/s) at Blackmans Bay STP for the year 2015. ..................... 37

Figure 10-6: CALMET wind direction (deg) at Blackmans Bay STP for the year 2015................. 38



EXECUTIVE SUMMARY

Meteorological Modelling for a full year period in 2015 has been conducted for Blackmans Bay Wastewater

Treatment Plant (WWTP) in Tasmania, hereafter referred to as Blackmans Bay STP. Meteorological data

from the year 2015 was chosen as it represents a recent year in a neutral El Nino year. The meteorological

data set has been custom built to the Blackmans Bay site. The meteorological model has used hourly

observational data from the Bureau of Meteorology’s four nearest meteorological stations which are Dennes

Point, Hobart, Kunyani and Grove plus a single upper air station, Hobart Airport. Two models, the Australian

CSIROs the Air Pollution Model (TAPM) and CALMET, the diagnostic meteorological component of the

CALPUFF suite of models, were used to develop the meteorological data set at the STP. Both models are

recognised as guideline models in Australia and New Zealand. Hourly observational data of temperature,

wind speed, direction, relative humidity and pressure were obtained from all four of the meteorological

stations.

As well as preparation of a one year meteorological data set, an analysis has been conducted on two historic

data sets that have been used in previous air analyses. The first is a December 2004 - December 2005

AUSPLUME-prepared meteorological data set from monitored data at Blackmans Bay. The second is an

AUSPLUME data set derived from TAPM data for 2006 which was used in odour modelling in 2014. An

evaluation of the monitored on-site data for 2005 suggests that the wind direction has been incorrectly

reported in the AUSPLUME meteorological file, and is likely to be 180 degrees out. This error was not

picked up in the 2014 modelling, and Blackmans Bay data was ruled as ‘unsuitable’ as the anemometer is

located on a building and does not meet the Australian Wind monitoring standards. However, when the wind

direction data is corrected, the data appears sound and reasonable and is acceptable for use in modelling. The

second data set, the 2006 AUSPLUME data set that was developed from TAPM data at the Blackmans Bay

site was used in the 2014 modelling. However, an in-depth analysis showed that the flow was constantly

dominated by westerly winds - even during the day when onshore sea breezes are common daily occurrence

especially in summer.

The new 2015 data, built for this air assessment has been exclusively developed from nearby observation

stations and Hobart Upper Air Data. TAPM 2015 data did not perform well and has mostly been excluded

from 2015 modelling. On evaluation of the CALMET model output at Blackmans Bay, there is a tendency

for the wind patterns to look fairly similar to Dennes Point. This is reasonable and expected due to the

nearness of Dennes Point to the STP. The important summertime and wintertime diurnal cycles are well

represented at Blackmans Bay STP, whereas they were not in the earlier data sets.

Development of a meteorological data set at Blackmans Bay STP is highly complex due to the large scale

topographic features upwind, the effects of the Peninsula, the sea breeze and the local topography around the

facility. It is a challenge to develop a meteorological data set at such a complex site. Hence it is highly

recommended to re-instate a meteorological station at Blackmans Bay STP to support future work. Further,

TasWater may elect to correct the 2005 on-site AUSPLUME meteorological data, and then use it directly in

CALPUFF to provide robustness to the 2015 modelling and to account for inter annual variability.



1 INTRODUCTION

1.1 BACKGROUND

TYR Group has engaged Jennifer Barclay to develop a meteorological data set in order to assess odours

from the Blackmans Bay STP. This report provides a detailed analysis of the meteorological data set

development for the STP.

1.2 PURPOSE OF THIS REPORT

The purpose of this report is to provide technical details of the methods used to develop and evaluate a

one year meteorological data set for Blackmans Bay STP. Further an analysis of two historic data sets

has been evaluated. These are the onsite 2005 AUSPLUME data set and the 2006 TAPM derived

AUSPLUME data set used in the 2014 modelling by Consulting Environmental Engineers (CEE).

This report provides TasWater with:

A suitable and reliable meteorological data set to use for use at Blackmans Bay for all air

modelling purposes both for the current set of conditions as well for any future developments

at the facility.

Confidence that the meteorological data has been prepared using state of science methods and

models

Technical document outlining the methods used to develop the 2015 Meteorological data set

A detailed evaluation of past meteorological data used for the STP

A detailed evaluation of the predicted model performance for 2015

1.2.1 Other relevant reports and Data

The following historical documents have been evaluated and assessed in my analysis of historic

meteorological modelling conducted at Blackmans Bay.

Report on Odour Modelling for Blackmans Bay Wastewater Treatment Plant, April 2014,

Consulting Environmental Engineers.

AUSPLUME meteorological data set- Blackmans Bay Site Winds -0405.met (supplied via

email from D. Fligelman from Ian Wallis on the 15 July 2016.

TAPM 2006 AUSPLUME Met Data set used in Consulting Environmental Engineers (CEE)

2014 Modelling Report.

An AUSPLUME December 2004 – December 2005 meteorological data set was developed sometime

after the data was collected and is the basis of several figures in the CEE, 2014 odour modelling report.

No modelling using this original on-site data set has been provided, and we are not aware of any

modelling undertaken prior to the CEE 2014 report.

Consulting Environmental Engineers conducted modelling in 2014 after developing a TAPM derived

AUSPLUME meteorological data for the year 2006 set at the site of the Blackmans Bay STP. The 2014

CEE report did not use the on-site meteorology, based on the observation that “The Blackmans Bay

monitoring station is attached to the top of a building and does not meet the Australian Standards for

wind monitoring”.

No sophisticated three-dimensional modelling appears to have been undertaken at the Blackmans Bay

site.

1.3 SCOPE OF REPORT

The development of a one year meteorological data set for Blackmans Bay STP includes the following

tasks;

1. Establish regional climate and site specific atmospheric dispersion potential.



2. Identify the local meteorological patterns at the Blackmans STP site and their capture in the

meteorological model

3. Evaluate the historic meteorological data sets and previous modelling to

4. Develop the best upper air data set suitable for dispersion of odour above 20m

5. Develop a realistic model grid resolution that allows a detailed description of the terrain

immediately around the facility as well as the larger scale topography.

6. Preparation of a draft report which summarises the methodology and findings of the study in

Technical Report.

7. Analyse all comments and submit a final report

This report includes the outcomes from items 1-6 listed above.



2 SITE DESCRIPTION AND HISTORIC DATA ANALYSIS

2.1 LOCATION

The Blackmans Bay STP is located some 15km south of Hobart. Figure 2-1 shows the current location

of the facility. The STP is located at approximately 30 m above sea level. Immediately around the

facility the terrain rises to over 150m within just 800m or so from the STP. The STP is located in a

depression, or an open gully. To the north the terrain rises up to a ridge at approximately 80m about

300m from the plant and to the south the terrain rises up to more than 100m about 600m from the plant.

Significant terrain >700m is within 15km of the STP site to the west.

Figure 2-1: Blackmans Bay Wastewater Treatment Plant.

2.2 HISTORIC DATA ANALYSIS

Unfortunately there is no recent on-site meteorological data of value to the meteorological data

development. Wind speed, wind direction and temperature was collected during December

2004 to December 2005, and developed into an AUSPLUME meteorological data set. This

data set has been referenced by CEE in their 2014 Odour Modelling report. The annual

Blackmans Bay STP wind rose presented in the CEE 2014 report is shown below on the left

hand side of Figure 2-2. Odour modelling was conducted at Blackmans Bay Treatment plant

by CEE in 2014, but did not use the 2005 Blackmans Bay data siting that the measured data

does not meet the Australian Standards for wind monitoring as the instruments are placed on

the building. Instead CEE developed a TAPM derived AUSPLUME meteorological data set

for 2006 at the site of the STP. The CEE report provided an annual wind rose of the 2006

TAPM data set at the site of the Blackmans Bay STP. This is shown in figure 9 of the 17B.3a

CEE-BB Odour Report April 2014.pdf and below in Figure 2-2 on the right hand side.

There are two striking points about the data;



1) The 2005 monitored Blackmans Bay data shows almost 90% easterly flow throughout

the year and,

2) The 2006 TAPM derived flows show almost 90% westerly flow for 2006.

2005 AUSPLUME met file of Blackmans Bay

Annual Wind Rose, CEE 2014 report, Figure 7.

2006 TAPM derived AUSPLUME met file of

Blackmans Bay Annual wind rose, CEE 2014 Report,

Figure 8.

Figure 2-2: Annual wind roses as displayed in the 2014 CEE report.

CEE used the 2006 AUSPLUME met file in their modelling.

Neither of these are representative of the Blackmans Bay site. Further analysis of the original

2005 AUSPLUME met data set shows that the wind directions are likely 180 degrees incorrect.

It seems that the wind directions have been incorrectly reported in the AUSPLUME

meteorological files as wind directions ‘blowing towards’ instead of winds ‘blowing from’.

Winds, ‘blowing towards’ are consistent with the old outdated Industrial Source Complex

Model (ISCST3) model formats, but not AUSPLUME. See Attachment A which shows that

the wind roses are the same in the original 2005 AUSPLUME data set as those reported in the

CEE report.



2005 Annual Blackmans Bay wind rose, which has

been corrected.

2006 TAPM derived AUSPLUME met file of

Blackmans Bay Annual wind rose, CEE 2014,

Figure 8.

Figure 2-3: Corrected 2005 Blackmans Bay Annual wind rose on left hand side with 2006 data used in the modelling by CEE in 2014.

When the wind direction is corrected then the Blackmans Bay winds looks much more realistic

of the annual flow conditions that you would expect at Blackmans Bay and also looks much

more similar to the 2006 TAPM derived data set used in the CEE 2014 modelling, (with the

exception of no easterly flow from the TAPM 2006 data set).

An analysis of the 2006 TAPM derived AUSPLUME data set used in the CEE 2014 modelling

shows that this data set is not suitable for Blackmans Bay. Attachment B shows the seasonal

and time of day roses from the TAPM derived data set. All the wind directions are from the

west and west south west with almost no north, east or southerly flow at all. This is not

possible. The Blackmans Bay STP is located on the east coast of Tasmania and diurnal sea and

land breezes are just part of the normal daily cycle. During the daytime, especially in summer

onshore easterlies will occur beginning at around 10am or earlier and gradually swinging to be

from the northeast in the late afternoon before collapsing around sunset where after the

nocturnal offshore land breeze occurs during the night. It is not clear why TAPM does not pick

up the easterly flow but it is possible that TAPM is over predicting the offshore land breeze

flow due to the over development of the katabatic flows off Mt Wellington which is located

just 15km to the west of Blackmans Bay.

2.3 METEOROLOGY OF BLACKMANS BAY

The meteorology at Blackmans Bay is complex - both on a local scale and on a larger regional

scale. On the regional scale, the facility is located on a Peninsula that juts out into the large

open Hobart Harbour. The coastline within the harbour is convoluted and significant

topography > 1000m exists within 15km to the west of the STP. On a local scale the STP is

located in a wide open gully, with elevated terrain 50m or higher than the STP to the north,

west and south of the facility.

The dominant flow at Blackmans Bay STP is from the west and southwest. In wintertime and

at night time (throughout the year) the flow is almost entirely from the west and west south

west. On a daily diurnal cycle, offshore land breezes occur every night. These stable offshore



flows are further assisted by katabatic flows off the higher topography to the west of the STP.

In winter on shore sea breeze flows are weak due to small land\sea temperature differences and

the offshore flows tend to dominate throughout the diurnal cycle. In the summer on shore sea

breezes are common during the daytime and occur regularly on the daily diurnal cycle.

The meteorological conditions at Blackmans Bay are described in the corrected 2005 wind roses of

Figure 2-4 below.



Blackmans Bay, Annual, 2005

(corrected)

Blackmans Bay, Summer 2005

(corrected)

Blackmans Bay, Winter 2005 (corrected)

Blackmans Bay, night time, (01h-06h)

2005 (corrected)

Blackmans Bay, morning, (07h-12h)

2005 (corrected)

Blackmans Bay, afternoon, (13h-18h)

2005 (corrected)

Blackmans Bay, evening, (19h-00h) 2005

(corrected)

Figure 2-4: Corrected 2005 Blackmans Bay wind roses. Wind is ‘blowing from’.



3 METEOROLOGICAL MODELLING

3.1 CALPUFF SUITE OF MODELS

CALPUFF is a multi-layer, multi-species non-steady-state puff dispersion model used to simulate the

effects of time and space-varying meteorological conditions on pollutant transport. It consists of three

main components: CALMET (a diagnostic 3-dimensional meteorological model), CALPUFF (an air

quality dispersion model), and CALPOST (a post-processing package). Geophysical data including land

use and terrain elevations at 200 m resolution are also processed and introduced into the wind field.

CALMET is a diagnostic meteorological model that is able to use both modelled (Predicted) weather

model data and surface observations. (Predicted modelled data can be used to describe the upper air

from 20m above the surface to 3000m above the surface when no suitable upper air data is available).

The output of CALMET is hourly varying meteorological data generated for every grid cell for 2015

both in the vertical and horizontal direction. The meteorological data is the combined effect of the initial

guess wind field derived from the observations and the final wind field which includes weighted surface

observation data. Upper air data from Hobart has been used. Cloud ceiling height and cloud cover were

expected to be sourced from Hobart Airport, but unfortunately none was available. TAPM cloud cover

and cloud ceiling height have been used at the location of Hobart Airport.

CALMET is recommended for use in all applications experiencing one or more of the following, all of

which are relevant to the Blackmans Bay STP;

Coastal environments e.g. sea breeze circulations and coastal fumigation

Complex terrain, non-steady state conditions

Surface temperature inversions

Extensive periods of calm or light winds.

CALMET is listed in the New South Wales Office of Environment and Heritage (OEH) ‘Approved

Methods for the Modelling and Assessment of Air Pollutants in NSW’ (August 2005), and, Good

Practice Guide for Atmospheric Dispersion Modelling, MFE, New Zealand (2006).

In order to capture important coastal and terrain-induced flows, CALMET was used to develop the 3-

dimensional hourly gridded meteorological domain. Inputs into CALMET included fine-scale terrain

(200 m resolution), nested land use data, surface observations and upper air data from Hobart Airport.

1km gridded TAPM data was evaluated for use in the modelling but was deemed unfit for purpose.

TAPM is Australia CSIRO’s Division of Atmospheric Research, ‘The Air Pollution Model’. The latest

versions of the model have been used. These include CALMET Version 6.5.0, Level 150223 and

CALPUFF Version 7.2.1, Level 150618.

3.1.1 Model Inputs

The following details were used to develop the 2015 meteorological model:

CALMET

A 26.4 km x 29.4 km meteorological model domain with 200m spacing over which the 3-

dimensional wind and temperature field were created. A total of 132 grid cells in the X direction

and 147 grid cells in the Y direction. The southwest corner coordinates are 513.63 km and

5224.971 km in the X and Y directions, respectively. The model uses a UTM coordinate system

with the WGS-84 worldwide Datum. The meteorological data set was developed from 4 nearby

hourly surface stations; Dennes Point, Hobart Airport, Grove and Kunyani. Upper air data from

Hobart was used to develop the upper air flow and temperature profile. Eleven vertical levels

were chosen.

TAPM



The TAPM air pollution was model was initially used to develop gridded 3-dimensional upper

air data to provide CALMET with an initial guess wind field. TAPM was run with four nested

grids. The outer nest was 36km, followed by a 12km nest inside the 36km nest, followed by a

4km nest and then lastly a 1km innermost nest. The TAPM model domain was centred on 43˚

0’ 00” S and 147˚ 19.5’ 00” E. The model domains assumed 35 x 35 grid cells and 35 vertical

levels. The outer TAPM domain covers a region of 1260 km x 1260 km. TAPM data was

evaluated for use in CALMET as both an hourly gridded 3-dimensional data set or as individual

vertical profiles to supplement the Hobart Radiosonde data. Unfortunately an evaluation of the

TAPM data showed that it was not performing well, so TAPM data either as gridded data or as

individual vertical profiles has not been used in the modelling. The TAPM data at the location

of Hobart Airport has been used to provide cloud cover and cloud ceiling height as this was not

provided even after request to Bureau of Meteorology for Hobart Airport.

A geophysical dataset including terrain and land use data to simulate the effects of the land

surface on plume dispersion. The SRTM (Shuttle Radar Topography Mission) terrain data has

a resolution of approximately 90 m. Land use data was obtained from the United States

Geological Survey (USGS).

3.2 LAND USE AND TERRAIN

The local land use around the Blackmans Bay STP consists of mixed agricultural land, pasture,

rangeland and urban areas. Forested areas are more prevalent to the west. Urban areas around the STP

are mostly residential. These land uses support a medium population density.

Terrain data used in the model is 90m SRTM3 satellite data. The gridded x (east-west), y (north-south)

and z (elevation) data is representative of the local terrain within the modelling domain and assists in

simulating the effects of land surface elevations on plume dispersion. Figure 3-1 shows a terrain map

of the entire region surrounding the STP. The CALMET model domain is shown as the first outer

magenta rectangle and the recommended CALPUFF domain is shown as the innermost magenta

rectangle. Figure 3-2 shows the CALMET model domain as well as the dominant Land Use types used

in the model, terrain contours and the location of the surface stations used in the modelling.



Figure 3-1: Terrain Map showing the local and regional features.

Figure 3-1 shows the local and regional topographic and coastline features affecting the

meteorology at Blackmans Bay STP. The outer magenta rectangle represents the CALMET

model domain and the inner rectangle represents the recommended CALPUFF computational

grid.



Figure 3-2: Land use and terrain contours.



4 CALMET OUTPUT

4.1 WIND SPEED AND DIRECTION

Figure 4-1 shows the annual, seasonal and time of day wind roses at Blackmans Bay as developed by

CALMET for 2015. Dennes Point, the closest observation station which is approximately 5km to the

south of the STP is also shown for brevity. Attachment C (Section 7) also shows the annual, seasonal

and time of day wind roses for each of the surface stations used in the modelling.

(Note that the wind rose is a graphical representation of the wind speed and direction. The direction of

the arm shows the direction from which the wind is blowing, the width of the arm segments shows the

speed of the wind, and the length of the arm shows the proportion of the time that wind speed is blowing

from that direction).

The CALMET wind roses are similar to those of Dennes Point which is not surprising due to their close

location. The dominant flow at both stations is west and west south west flow. Easterly flows are

infrequent and only occur for a short time in the morning between 07h00 and 12h00 and in the afternoon

between 13h00 and 18h00. At Blackmans Bay STP, easterly flow occurs for 25% of all winds during

the summer months, but only 1.8% of all winds during the winter months. Easterly flows account for

11.5% of all data between 07h00 and 12h00 and 30.5% of all data between 13h00 and 18h00. Light

south and south easterly winds (<1.8 m/s) occur between the hours of 13h00 and 00h00 and account for

4.6% of all winds.

It is understood that odour complaints occur on the ridge to the north north west of the STP and that

complaints have occurred mostly in the late afternoon and early evening. Worst case odour conditions

can be expected anytime of the day when the winds are light from the south or south east. They are also

likely to occur at any time in the day when there is a major change in wind direction and wind speed.

Typically, when the wind speed drops the wind direction becomes highly variable. This wind speed

and direction change can happen in the evenings around sunset when the mixing height collapses and

in the early morning hours around sunrise and for a few hours afterward. Worst case odour dispersion

conditions can also occur with the onset of local upslope flows during the morning hours.

Dennes Point Annual

Blackmans Bay CALMET, 2015, Annual



Dennes Point Summer

Blackmans Bay CALMET, 2015, Summer

Dennes Point Winter

Blackmans Bay CALMET, 2015, Winter

Dennes Point 01h-06h Night time

Blackmans Bay 01h-06h Night time, CALMET 2015



Dennes Point 07h-12h Morning

Blackmans Bay 07h-12h Morning, CALMET 2015

Dennes Point 13h-18h Afternoon

Blackmans Bay 13h-18h Afternoon, CALMET 2015

Dennes Point 19h-00h Evening

Blackmans Bay 19h-06h Evening, CALMET 2015

Figure 4-1: Annual, Seasonal and time of day Wind Roses from the Wiri Meteorological site, 2010.



The wind direction is read as the wind blowing ‘from’. Hence, the afternoon wind rose for

Wiri shows dominant flows from the southwest.

4.4.1 Calm and Light Winds

Worst case odour dispersion is usually associated with calm and light wind speed events.

Under these conditions, odour stagnates and accumulates and will only be advected under

either mechanical or convective conditions. Mechanical conditions could be at night or

convective conditions after sunrise during the day. An analysis of the light winds at

Blackmans Bay STP are analysed and presented below in Table 4-1. It is important to note

that there are very few complete calm events at the STP, but the wind is often light, with the

onsite data recording up to 42% of all night time hours (01h-06h) in the range of 1 – 2.1

m/s.

Table 4-1: Calm and light wind speed events between the CALMET Model (2015) and Blackmans Bay onsite data in 2005.

Calm

winds

<0.1 m/s %

0.1–0.5 m/s

%

0.5–1.0

m/s

%

1–2 m/s

%

Total

(%)

CALMET Summer 0.05 1.6 5 14 20.7

2015 Winter 0.14 1.9 4.2 15 22.5

01h – 06h 0.05 1.74 5 17 24.0

07h - 12h 0.1 1.7 5.3 17 25.1

13h – 18h 0.05 1.3 3 9.6 14.3

19h – 00h 0.2 2.4 5.6 18 26.0

% <0.5

m/s*1

% 0.5-2.1

m/s

Blackmans 01h – 06h 0 42.0 42.0

Bay 2005 07h - 12h 0 29.9 29.9

13h – 18h 0 14.9 14.9

19h – 00h 0 30.9 30.9

*1 the 2005 Blackmans Bay STP data set is in AUSPLUME format. AUSPLUME does not read any wind speed <0.5 m/s.

It is not known if the true number of calms (<0.5 m/s) have been removed from the data set, or they have been increased

to be equal to 0.5 m/s.

Other important points gleaned from the analysis of the 2015 CALMET output at Blackmans

Bay and the 2005 Blackmans Bay data are detailed below.

For Summer:

27.6% of all the data (January, February, December 2015) is from an easterly

direction with a wind speed of between 3 – 5 m/s. This mostly happens between the

hours of 13h – 18h and is consistent with afternoon sea breezes.

36.9% of all summer time flow is from a westerly direction (W, SW and WSW) with

wind speeds > 5 m/s. This mostly occurs during the night between 19h-06h. This

flow is consistent with nocturnal drainage flows commonly called Katabatic winds.

A katabatic wind carries high density air from a higher elevation down a slope under

the force of gravity. These winds originate from radiational cooling of air on top of

the elevated terrain west of the STP. As the air density is inversely proportional to

temperature the air flows downwards and is usually stronger in summer.



Westerly flow in the range 0.1 – 5 m/s can also occur at other times of the day in

summer and is likely due to synoptic conditions.

For Winter:

In winter 27.6% of all the winter data (June, July, August) is from a westerly

direction (W, SW and WSW) in the range 3 – 5 m/s, and;

33% of all winter W, SW and WSW flow is > 5 m/s. This percentage is lower than

in summer where nearly 37% of all summertime westerly flow is > 5m/s. The reason

for this is largely temperature driven, and drainage flows during winter may not be

as strong.

The westerly flow in winter is much more evenly spread between all the wind speed

ranges than during the summer months.

4.2 REPRESENTATIVE YEAR

2015 was chosen as the representative year for modelling due to it being a recent year. Wind

instruments, and information about the sites is readily available and the equipment is more

likely to be new and more accurate than less recent years. 2015 was a neutral El Nino year.

For model robustness and to examine inter-annual variability I recommend adding the 2005

Blackmans data as a second model year. It is advisable to begin with the raw meteorological

data records and correct both the wind direction likely 180 degree error and calm winds <

0.5 m/s.

4.3 CALMET – GENERATED SPATIAL WIND FIELDS

Figure 4-2 shows a spatial distribution plot of the 10m wind field as created by CALMET using

a combination of surface observations (Dennes Point, Grove, Hobart Airport and Kunyani).

The plot provides a snap shot of the surface level winds across the CALMET modelling domain

for a single hour of the CALMET model run (3 January hour 03h). The length of the wind

vector represents the wind speed; the longer the vector, the stronger the wind speed. The range

of wind speed in Figure 4-2 is from < 1 m/s to 12 m/s. Only every 9th wind vector is shown.

The spatial wind field plot is a representation of stable atmospheric conditions. At the site of

the STP the winds are very light and highly variable. However, on top of the elevated terrain

to the west, the flow is strongly west. Strong flow at high elevations is consistent with low

pressure across the mountain tops. These strong terrain driven westerly flows have a significant

impact on wind patterns at Blackmans Bay STP and are responsible for most of the west winds

at the STP throughout the year.

4.4 UPPER AIR DATA

Upper air data from Hobart Airport has been used to develop the upper air wind field above

20m. Figure 4-2 shows the quantity of Radiosonde profiles during 2015 and the times that

they occurred in UTC time. The Radiosonde data was mostly of a good quality with enough

soundings happening prior to sunrise and around sunset to make the data useful.

Upper air data is critical in determining the temperature profile and for developing the 3-

dimensional wind flow above the surface. Three dimensional gridded TAPM data was

originally developed to provide the three dimensional wind field to CALMET. However,

an evaluation of the quality of the 2015 TAPM data showed that it was not doing well at the

nearest observation site to the STP, Dennes Point. The statistical evaluation is shown in

Attachment D, Section 9 of this report. Briefly, only between 34% and 42% of all the data

analysed met the statistical bench mark values for wind speed and direction. TAPM failed



the wind speed Root Mean Square Error (RMSE) bench of < 2 m/s with a value of 2.22 m/s

for RMSE. The wind direction failed the Gross Error bench of < 30˚ with a value of 37˚.

The temperature statistics were poor with TAPM showing a strong negative bias (under

predicting the winds). Only between 20% and 37% of all data met the temperature bench

criteria for Index of Agreement and Bias. Because TAPM did not perform well at the nearest

surface station to the STP. TAPM data was only used to represent the cloud cover and cloud

ceiling height as this was missing from the Hobart Airport records. TAPM data was also

used to repair and replace certain missing upper air soundings from Hobart Airport.

The surface data was vertically extrapolated and the Bias values in CALMET were

switched on to not use the Hobart data in the first two vertical levels.

Figure 4-2: Chart plot showing the quantity and times of Hobart Radiosonde in 2015, UTC time.

0

50

100

150

200

250

300

350

400

10

am

11

am

12

pm

13

pm

14

pm

15

pm

16

pm

17

pm

18

pm

19

pm

20

pm

21

pm

22

pm

23

pm

1am

2am

3am

4am

5am

6am

7am

8am

9am

10

am

Hobart radiosondes, 2015

Hobart Airport Radiosonde…



Figure 4-3: Base Map showing the CALMET meteorological modelling domain (coloured area) with terrain contours for 2015 modelling.

Wind vectors for 3 January hour 23h00 are overlaid on Figure 4-3. The meteorological

conditions are stable with very light variable winds (< 1 m/s) at Blackmans Bay STP. Strong

flow (~ 12m/s) on the top of Mt Wellington are normal. Katabatic winds off the elevated

topography assist the nocturnal offshore flow at nights and during the winter months.



5 CONCLUSIONS

Meteorological Modelling for a full year period in 2015 has been conducted for Blackmans Bay

Wastewater Treatment Plant (WWTP) in Tasmania. The meteorological data set was custom built to

the Blackmans Bay site by using hourly observational data from the Bureau of Meteorology’s four

nearest meteorological stations which are Dennes Point, Hobart, Kunyani and Grove. Upper air data

from Hobart Airport was used to develop the upper air winds and temperature profile.

Two models, the Australian CSIROs the Air Pollution Model (TAPM) and CALMET, the diagnostic

meteorological component of the CALPUFF suite of models were used to develop the meteorological

data set at the STP. Both models are recognised as guideline models in Australia and New Zealand.

The TAPM data at Hobart was only used to repair some of the Hobart Radiosonde soundings and to

represent cloud cover as this was unavailable from Hobart Airport.

As well as preparing a one year meteorological data set, an analysis has been conducted on two historic

data sets that have been used in previous air analyses. The first is a December 2004 - December 2005

AUSPLUME prepared meteorological data set from monitored data at Blackmans Bay. The second is

an AUSPLUME data set derived from TAPM data for 2006 which was used in odour modelling in

2014. An evaluation of the monitored on-site data for 2005 suggests that the wind direction has been

incorrectly reported in the AUSPLUME meteorological file and is likely 180 degrees out. In the 2014

modelling, the Blackmans Bay data was ruled as ‘unsuitable’ as the anemometer is located on a building

and does not meet the Australian Wind monitoring standards (rather than the likely 180 degree error).

However, when the wind direction data is corrected, the data appears sound and reasonable and is

acceptable for use in modelling. The second data set, the 2006 AUSPLUME data set that was developed

from TAPM data at the Blackmans Bay site was used in the 2014 modelling. However, an analysis

showed that this data set was also flawed with westerly winds occurring almost constantly as well as

through the day time during summer when onshore sea breezes occur.

Worst case dispersion conditions and potential complaints from the STP can be expected to occur under

any of the following conditions;

- Any time of the day when the winds are light or from the southeast or east.

- Any time of the day when there is a major change in wind direction and wind speed.

o This could occur mid-morning with the onset of the sea breeze. The wind direction

will typically swing right around from an off shore westerly to an onshore south

easterly, gradually becoming more easterly and stronger throughout the day.

o This could occur in the early evening around sunset when the onshore sea breeze

collapses along with the mixing height. The wind direction can become very

variable for a time before taking up its regular night time westerly flow.

- Onset of temperature driven local upslope flows during the morning hours following

sunrise. Under these conditions odour which has accumulated during the night can disperse

upslope.

- Stable atmospheric conditions. Under these conditions which can occur every night, there

is likely to be a surface based temperature inversion which can cause odour to be trapped

allowing odour to stagnate in the stable layers close to the surface.

Development of a meteorological data set at Blackmans Bay STP is highly complex due to the large

scale topographic features upwind, the effects of the Peninsula, the sea breeze and the local topography

around the facility. It is a challenge to develop a meteorological data set at such a complex site. Hence

it is highly recommended to re-instate a meteorological station at Blackmans Bay STP to support future

works. Further, TasWater may elect to utilise the corrected 2005 on-site AUSPLUME meteorological

data directly in CALPUFF to provide robustness to the 2015 modelling and to account for inter annual

variability.



6 ATTACHMENT A – WIND ROSES FROM DEC 2004 – DEC 2005

BLACKMANS BAY

Wind roses from historic Blackmans Bay 2004-2005 meteorological data set. Wind roses on

the left hand side are those as reported in the 2014 CEE report and the winds on the right hand

side are the ones from the 2005 Ausplume data set. The reporting of the 2005 winds in the

previous 2014 modelling undertaken for the site are incorrect, and data is also incorrectly

written into the Ausplume met data file.

Blackmans Bay, 2005,(night hours), as reported in

2014 CEE Pty Ltd (wind blowing from)

Blackmans Bay, 2005, 01h-06h, Ausplume Met Data

(Wallis)

Blackmans Bay (day hours), CEE Pty Ltd (wind

blowing from)

Blackmans Bay, 2005, 13h-18h, AusplumeMetData

(Wallis)



7 ATTACHMENT B – WIND ROSES FOR TAPM DERIVED AUSPLUME 2006 DATA AS IN 2014 MODELLING

TAPM 2006 Autumn

TAPM 2006 Winter

TAPM 2006 Spring

TAPM 2006 – Night time Hours 01h -06h

TAPM 2006 – Morning Hours 07h -12h

TAPM 2006 – Afternoon Hours 13h -18h



TAPM 2006 – Evening Hours 19h -00h



8 ATTACHMENT C – TIME OF DAY WIND ROSES AT SURFACE OBSERVATION SITES AS USED IN THE 2015,

CURRENT MODELLING

Figure 8-1: Annual, Seasonal and Time of day Wind Roses from Hobart, Dennes Point, Grove and Kunyani for 2015.

The wind direction is read as the wind blowing ‘from’. West and south westerly flow is the dominant flow throughout the year at Blackmans Bay STP.

Hobart Annual

Dennes Point Annual

Grove Annual

Kunyani Annual



Hobart Summer

Dennes Point Summer

Grove Summer

Kunyani Summer

Hobart Winter

Dennes Point Winter

Grove Winter

Kunyani Winter



Hobart 01h-06h Night time

Dennes Point 01h-06h Night time

Grove 01h-06h Night time

Kunyani 01h-06h Night time

Hobart 07h-12h Morning

Dennes Point 07h-12h Morning

Grove 07h-12h Morning

Kunyani 07h-12h Morning



Hobart 13h-18h Afternoon

Dennes Point 13h-18h Afternoon

Grove 13h-18h Afternoon

Kunyani 13h-18h Afternoon

Hobart 19h-00h Evening

Dennes Point 19h-00h Evening

Grove 19h-00h Evening

Kunyani 19h-00h Evening



9 ATTACHMENT D TAPM EVALUATION

9.1 METEOROLOGICAL EVALUATION

An evaluation of the 2015 TAPM data has been conducted at the nearest observation site to the TAPM

grid point. The evaluation consists of quantitative statistical comparisons of two meteorological datasets

in this case the predicted 1km TAPM model output has been compared to the Dennes Point observation

station for a couple of months in summer 2015. The statistical output is evaluated using benchmarks

developed by Emery et al. (2001) and Tesche et al. (2001). These statistical benchmark measures are

listed in Table 9-1 and the results in Table 9-2.

Table 9-1 Benchmarks for prognostic modelling evaluation

Wind speed Wind direction Temperature Humidity

IOA ≥0.6 -- ≥0.8 ≥0.6

RMSE ≤ 2 m/s -- -- --

Mean Bias ≤ ±0.5 m/s ≤ ±10° ≤ ±0.5 K ≤ ±1 g/kg

Gross Error -- ≤ 30° ≤ 2 K ≤ 2 g/kg

The TAPM gridded data was interpolated to the nearest grid cell closest to the Dennes Point

observation site. The statistical measures include;

Mean value (e.g. mean observation and mean prediction)

Bias error (average difference, e.g. predicted – observation)

Gross or Absolute error (average of the absolute value of the e.g. |Predicted –

Observation| values)

Root-mean-square error (RMSE), including its systematic (RMSEs) and unsystematic

(RMSEu) components

Index of Agreement (IOA) (based on the approach of Wilmont 1981). A perfect score

is 1.

The bias and gross errors for wind speed and direction are computed from the wind speed and

wind direction values, not the U and V components of the winds

Table 9-2. Statistical evaluation between 1km TAPM and nearest observation for wind speed (m/s), wind direction (degrees) and Temperature (K).

Wind speed (m/s)

IOA Bias RMSE RMSES/

RMSE

Gross Error

Maximum 0.85 2.86 3.97 0.99 3.29

Minimum 0.21 -2.77 0.86 0.20 0.68

Mean 0.60 -0.1 2.22 0.78 1.81

Benchmark 0.6 0.5 2.0

Fraction meeting the benchmark 0.57 0.37 0.47

Total # days 30 30 30 30 30



Wind direction (deg)

Bias Gross Error

Maximum 35.04 106.61

Minimum -49.05 11.08

Mean 3.49 36.91

Benchmark 10.00 30.0

Fraction meeting the benchmark 0.37 0.47

Total # days 30 30

Temperature (K)

IOA Bias Gross Error RMSE RMSES/RMSE

Maximum 0.97 1.12 2.94 3.30 1.00

Minimum 0.45 -2.94 0.62 0.94 0.29

Mean 0.72 -1.04 1.55 1.85 0.86

Benchmark 0.80 0.50 2.00


Total # days 30 30 30 30 30

Specific Humidity (g/kg)

IOA Bias Gross Error RMSE RMSES/

RMSE

Maximum 0.94 0.55 1.40 1.7 1.0

Minimum 0.09 -1.4 0.31 0.4 0.27

Mean 0.51 -0.39 0.80 0.94 0.85

Benchmark 0.6 1.0 2.0


Total # days 30 30 30 30 30



10 ATTACHMENT E METEOROLOGY AT BLACKMANS BAY

10.1 CALMET OUTPUT

Figure 10-1: CALMET stability classes at Blackmans Bay STP for the year 2015.

The plot shows the diurnal scatter of atmospheric stability by time of day. 1 means unstable conditions and 6 stable conditions. The plot below is normal and expected conditions for Blackmans Bay, Unstable conditions are normal during the day, whilst stable conditions occur at night time.

0

1

2

3

4

5

6

7

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

STA

B_C

LASS

(G

/KG

)

Hours

01 Jan-2015, 1:00:00 AM To 01 Jan-2016, 1:00:00 AMSTABILITY CLASS

Diurnal Variability



Figure 10-2: CALMET short wave radiation (W/m2) at Blackmans Bay STP for the year 2015.

The plot shows the diurnal scatter of short wave radiation by time of day. Maximum insolation occurs during the middle of the day, shortwave radiation is zero at night time.

0

100

200

300

400

500

600

700

800

900

1000

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

SHO

RT_

WA

VE

(K

)

Hours

01 Jan-2015, 1:00:00 AM To 01 Jan-2016, 1:00:00 AMSHORT_WAVE RADIATION (W/m2)

Diurnal Variation



Figure 10-3: CALMET mixing height (m) at Blackmans Bay STP for the year 2015.

The plot shows the diurnal scatter of mixing height by time of day. The maximum daily mixing height is just over 2000m but the bulk of the time the mixing height is around 1200m. This is not unexpected for a site close to the ocean.

0

500

1000

1500

2000

2500

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

MIX

HG

T (

MET

ERS)

Hours

01 Jan-2015, 1:00:00 AM To 01 Jan-2016, 1:00:00 AMMIXING HEIGHT (m)

Diurnal Variation



Figure 10-4: CALMET temperature (K) at Blackmans Bay STP for the year 2015.

The plot shows the diurnal scatter of temperature by time of day. The mean temperature at

Blackmans Bay STP is between 280K and 285K, i.e., around 12˚C. The temperature drops

below freezing (273˚K) in the early hours of the morning between 00h00 and 07h00. These

will be winter hours. In the middle of the day the maximum temperatures are around 22˚C.

265

270

275

280

285

290

295

300

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

TEM

P (

K)

Hours

01 Jan-2015, 1:00:00 AM To 01 Jan-2016, 1:00:00 AMTEMPERATURE at 10m

DIurnal Variation



Figure 10-5: CALMET wind speed (m/s) at Blackmans Bay STP for the year 2015.

The plot shows the diurnal scatter of wind speed by time of day. Blackmans Bay STP records some strong winds (>10m/s).

0

5

10

15

20

25

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

WSP

EED

(M

/S)

Hours

01 Jan-2015, 1:00:00 AM To 01 Jan-2016, 1:00:00 AMWIND SPEED (m/s) at 10m

Diurnal Variation



Figure 10-6: CALMET wind direction (deg) at Blackmans Bay STP for the year 2015.

The plot shows the diurnal scatter of wind direction by time of day. The absence of onshore easterly flow (sea breeze) is absent completely between the hours of 00h00 and 07h00 and again from approximately 21h00 to 23h00.

0

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100

150

200

250

300

350

400

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

WD

IR (

DEG

REE

S)

Hours

report blackmans bay wastewater treatment … blackmans bay...2014 and summarised in the ‘report...

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